S. Eilenberg, Automata, Languages and machines, Volume A. Academic Press.

M. Holcombe, Systems, machines and algebra, BCS-FACS (6). 1984.

M. Holcombe, Formal methods in the specification of the human-machine interface, International C.I.S. Journal. 1(2),1987,24-34.

M. Holcombe, Goal-directed task analysis, Int. CIS Journal, 1(4), 14-22.

M. Stannett, An organisational approach to decision-making in command systems. International CIS Journal. 1, 23-34.

M. Holcombe, Algebraic techniques in system specification, Bull. Irish Math. Soc. 21, 13-28,

M. Holcombe, X-machines as a basis for dynamic systems specification, Software Engineering Journal, 3(2), 69-76.

M. Holcombe, Software Engineering, in Trends in Information Technology. Ed. D.Linkens & R. Nicolson.Peregrinus, pp 17- 36.

M. Stannett, Implications of X-machines and the Halting Problem: Building a super-Turing machine for computational AI, AISB Quarterly 74.

M. Stannett, X-machines and the Halting Problem: Building a super-Turing machine, Formal Aspects of Computing 2, 331-41.

M. Stannett, An Introduction to post-Newtonian and non-Turing Computation, Technical Report, Department of Computer Science, University of Sheffield, CS-91-02.

S. Clarke, The Modelling and Evaluation of the Human-Computer Interface, PhD thesis, University of Sheffield.

G. Laycock, The Theory and Practice of Specification-Based Software Testing, PhD thesis, University of Sheffield.

M. Holcombe, An integrated methodology for the formal specification, verification and testing of systems, Proc. Eurostar 93, London.

M. Holcombe, From VLSI through machine models to cellular metabolism, in R.Paton, Computing with biological metaphors Chapman & Hall.

M. Holcombe and R.Paton, Computational models of cellular information systems, IEE Coll. Molecular Bioinformatics, London, 3/1 - 3/5.

R. Paton and M. Holcombe, Computational models of cellular information systems, in Advances in Molecular Bioinformatics, ed. S. Schulze-Kremer, IOS Press.

Z. Duan, M. Holcombe and D. Linkens, Timed interval temporal logic and the modelling of hybrid systems, Pro. Eur. Simulation Multi-Conference, Barcelona, 534-541.

M. Fairtlough, M. Holcombe, F. Ipate, C. Jordan, G. Laycock and Z. Duan. Using an X-machine to model a video cassette recorder, Current issues in Electronic modelling 3, 141-151.

Z. Duan, M. Holcombe and D.A. Linkens, Modelling of a Soaking Pit Furnace in Hybrid Machines, Systems Analysis, Modelling, and Simulation. 18, 153-157.

Z. H. Duan, M. Holcombe and D. A. Linkens, Specification of a Soaking Pit System in Parallel Hybrid Machines, in Proceedings of the 21 Euromicro Conference, IEEE/CS, p241-247, Como, Italy, September 4-7.

M. Holcombe, F.Ipate and A. Grondoudis, Complete functional testing of safety critical systems. Proc. IFAC Workshop on Emerging Control Technologies. Florida, 343-358.

F. Ipate, Theory of X-machines and Applications in Specification and Testing, PhD Thesis, University of Sheffield.

A. Bell and M. Holcombe,Computational models of cellular processing, Proc. Conf. on Information Processing in Cells and Tissues '95. Liverpool, 171-184.

F. Ipate, X-machine Based Testing, in Proceedings of the 10th International Conference on Control Systems and Computer Science, Vol. 2, Bucharest, 262 - 272.

J. Barnard, C. Theaker, J. Whitworth & M.Woodward, Real-time communicating X-machines for the formal design of real-time systems, Proceedings of DARTS '95, Universite Libre, Brussels, Belguim, November 9-11th.

E. Berki, & D. Novakovic, Towards an Integrated Specification Environment (ISE), In the Proc. of the 5th Hellenic International Conference of Informatics, Athens, GREECE.

F. Ipate, X-machine based testing, in Proceedings of 10th Int. Conf. Control Systems and Computer Science, Vol. 2, Bucharest, pp. 262-272.

Z. H. Duan and M. Holcombe, From Requirements to Specifications for Hybrid Systems, Proceedings of the International Symposium on Future Software Technology, Xian, China, Oct 9-11, 239--246.

F. Ipate and M. Holcombe, Another look at computability, Informatica, 20, 359-372.

A. Bell and M. Holcombe, Computational models of cellular processing, in Computation in Cellular and Molecular Biological Systems. M. Holcombe, R. Paton and R. Cuthbertson (Eds.) , World Scientific Press, Singapore.

J. Barnard, J. Whitworth and M. Woodward, Communicating X-machines, Information and Software Technology, 38, 401-407.

Z. Duan, Modelling of Hybrid Systems, PhD thesis, University of Sheffield.

E. Berki & E. Georgiadou, Towards resolving Data Flow Diagramming Deficiencies by using Finite State Machines, 5th Software Quality Conference, Universities of Abertay Dundee & Humberside, ISBN: 1 899796 02 9, Scotland, UK.

E. Georgiadou & E. Berki, Improving Systems Specification Understandability by Using a Hybrid Approach, First International Conference on Software Process Improvement, Research, Education and Training, (INSPIRE '96), The British Computer Society, ISBN: 1899621113, Bilbao, SPAIN.

K. Bogdanov, M. Fairtlough, M. Holcombe, F. Ipate and C. Jordan, X-machine Specification and Refinement of Digital Devices, Department of Computer Science Internal Report, CS - 97 - 16, University of Sheffield.

F. Ipate and M. Holcombe, An Integration Testing method which is proved to find all faults. Int. Jour. Comp.Math. 63, 159-178.

M. Holcombe, When testing is done. Proc. EuroSTAR97, Edinburgh.

F. Ipate, Is software testing effective?, in Proceedings of the 3rd International Symposium of Economic Informatics, Bucharest, 173-179.

K. Siakas, E. Berki, E. Georgiadou, & C. Sadler,The Complete Alphabet of Quality Information Systems: Conflicts & Compromises ", 7th World Congress on Total Quality Management (TQM '97), McGraw-Hill, ISBN 0-07-463186-1, N. Delhi, INDIA.

E. Berki, E. Georgiadou & K. Siakas, A Methodology is as strong as the degree of user involvement it supports, Proceedings of the International Symposium on Software Engineering in the Universities (ISSEU '97), Rovaniemi, FINLAND.

S. Bavan, E. Berki, E. Georgiadou, M. Milankovic-Atkinson & M. Walker, Towards a Formal Specification of an Object-Oriented Parallel Architecture, International Conference for Parallel and Distributed Processing Techniques and Applications (PDPTA), Volume II, ISBN: 0-9648666-6-8, Las Vegas, USA.

F. Ipate, Is Software Testing Effective? in proceedings of 3rd. Int. Symposium of Economic Informatics, Bucharest, pp. 173-179.

F. Ipate and M. Holcombe, A method for refining and testing generalised machine specifications. Int. Jour. Comp. Math. 68, 197-219.

F. Ipate & M. Holcombe. Specification and testing using generalised machines: a presentation and a case study. Software testing, Verification and Reliability, 8, 61-81.

K. Bogdanov and M. Holcombe, Automated Test Set Generation for Statecharts, in Applied Formal Methods FM-Trends 98 (Boppard, Germany), D. Hutter, W. Stephan, P. Traverso & M. Ullmann (Editors), Springer LNCS Series, 1641.

A. Bell and M. Holcombe, Computational models of immunological systems. In Information Processing in Cells and Tissues , (eds.) M. Holcombe & R. Paton, 213-226. Plenum Press.

M. Holcombe and F. Ipate, Correct systems - building a business process solution. Springer, Applied Computing Series.

A. Bell, Formal Computational Models of Biological Systems, PhD thesis, University of Sheffield.

J. Barnard, COMX: a design methodology using communicating X-machines, Inform. Software Tech 40(5-6), 271-280.

E. Berki & E. Georgiadou, A Comparison of Qualitative Frameworks for Information Systems Development Methodologies, Proceedings of The Twelfth International Conference of The Israel Society for Quality, Jerusalem, ISRAEL.

T. Balanescu, A. J. Cowling, H. Georgescu, M. Gheorghe, M. Holcombe and C. Vertan. Communicating Stream X-machines Systems are no more than X-machines. Journal of Universal Computer Science, Volume 5, no. 9, 494-507.

P. Kefalas and E. Kapeti, A Design Language and Tool for X-Machines Specification in Advances in Informatics, edited by D. I. Fotiadis, S. D. Nikolopoulos, World Scientific.

Barnard J, Object COMX: Methodology using communicating X-machine objects, J Object-oriented Prog. 12(7), 12-17.

F. Ipate, Using Hybrid Machines for specifying Hybrid Software Systems, in Proceedings of the 4th International Symposium of Economic Informatics, Bucharest, 679-686.

F. Ipate, Using Hybrid Machines for Specifying Hybrid Software Systems, in Proceedings of 4th Int. Symp. of Economic Informatics, Bucharest, pp. 679-686.

F. Ipate, A method for testing non-deterministic X-machines that finds all faults, to appear in Proc. CAIM 1999, Pitesti.

T. Balanescu, M. Gheorghe, M. Holcombe, Deterministic stream X-machines based on grammar systems in Words, sequences, grammars, languages: where biology, computer science, linguistics and mathematics meet, Volume I, Ed. C. Martin-Vide & V. Mitrana, Kluwer.

F. Ipate & M. Holcombe, Testing non-deterministic X-machines , in Words, sequences, grammars, languages: where biology, computer science, linguistics and mathematics meet, Volume II, Ed. C. Martin-Vide & V. Mitrana, Kluwer.

M. Holcombe, X-machines in Computing, Biology and Art . Proceedings, Grammar Systems 2000, ed. R. Freund & A. Kelemenova, Silesian University at Opava, Czech Republic, ISBN 80-7248-067-7, 343-346.

T. Balanescu, M. Gheorghe & M. Holcombe, A subclass of stream X-machines with underlying distributed grammars, Proceedings, Grammar Systems 2000, ed. R. Freund & A. Kelemenova, Silesian University at Opava, Czech republic, ISBN 80-7248-067-7, 93-112.

Z. Duan, M. Holcombe, A. Bell, "A logic for Biological Systems", Biosystems, 55(1-3), 93-105.

G. Eleftherakis, Model Checking and X-machine Specification, Technical Report, CS-02/00, City College, Thessaloniki, Greece.

E. Kehris, G. Eleftherakis, and P. Kefalas, Using X-machines to Model and Test Discrete Event Simulation Programs, in Proceedings of the 4th World MultiConference on Circuits, Systems, Communications and Computers (CSCC), Athens.

P. Kefalas and A. Sotiriadou, Transforming X-machines to Z Specifications, Technical Report, CS-06/00, City College, Thessaloniki, Greece

P. Kefalas, X-machine Description Language: User Manual, version 1.6, Technical Report, CS-07/00, City College, Thessaloniki, Greece.

P. Kefalas and E. Kapeti, A Design Language and Tool for X-machine Specification, in Advances in Informatics, (D. I. Fotadis and S. D. Nikolopoulos eds.), World Scientific, 134-145.

H. Georgescu and C. Vertan, A New Approach to Communicating Stream X-machines, Journal of Universal Computer Science, 6 (5) 490-502.

P. Kefalas, Automatic translation from X-machines to Prolog, Technical Report, CS-01/00, City College, Thessaloniki, Greece.

K. Bogdanov and M. Holcombe, Statechart Testing Method for Aircraft Control, To appear, Software Testing, Verification and Reliability.

P. Kefalas, Modelling an Agent Reactive Architecture with X-machines, Technical Report, CS-01/00, City College, Thessaloniki, Greece.

P. Kefalas, G. Eleftherakis and E. Kehris, Communicating X-machines: a Practical Approach for Modular Specification of Large Systems, Technical Report, CS-09/00, City College, Thessaloniki, Greece.

S. Vanak, X-Machines + L-Systems = XL-Systems, International Conference on Computer Graphics 2000, Geneva, Switzerland, 127-134.

K. Bogdanov, Automated Testing of Harel's Statecharts, PhD thesis, University of Sheffield.

S. Chambers, Applying X-Machines in the Retrospective Analysis and Testing of Computer Software, PhD thesis, University of Sheffield.

C. Chambers, Industrial Strength Techniques for the Development of PLC-Based Safety-Related Control and Protection Systems, PhD thesis, University of Sheffield.

A. Grondoudis, X-Machine Based Specification and Design for Testing of the CATV Protocol, PhD thesis, University of Sheffield.

M. Holcombe, T. Balanescu, M. Gheorghe and P.Radovici-Marculescu, On testing generalized stream X-machines, in Gh Paun (Ed), Recent topics in Mathematical Computational Linguistics, Romanian Academy Publishing House, 130-141

F. Ipate and M.Popescu, A Z Type Language for Specifying X-Machines, in Proceedings of CITTI, Constanta, Romania, 82-88.

F. Ipate, A Theory of Testing for X-machines, in Proceedings of CAIM 2000 (Conference on Applied and Industrial Mathematics), Pitesti, Romania.

E. Berki, Process Metamodels and Method Engineering in Software Process Improvement, in the Proc. of the BCS INSPIRE IV Conference: Training and Teaching for the Understanding of Software Quality, ISBN 1-902505-36-0, Sep. 2000, University of North London, UK.

M. Holcombe, F. Ipate and K. Bogdanov, Total Software Testing, to appear in Proc. ICSTEST, Bonn, Germany.

G. Eleftherakis and P. Kefalas, Model Checking Safety-Critical Systems Specified as X-Machines, to appear in Annals of Bucharest University.

R. Hierons & M. Harman, Testing against non-deterministic stream X-machines. To appear in FACS.

M. Gheorghe, Generalised stream X-machines and cooperating distributed grammar systems. To appear in FACS.

T. Balanescu, Generalised stream X-machines with output delimited type. To appear in FACS.

F. Ipate & M. Holcombe, Generating test sequences from non-deterministic X-machines. To appear in FACS.

A. Cowling, H. Georgescu & C. Vertan, A structured way to use channels for communication in X-machine systems. To appear in FACS.