1. Shop problems with two machines and time lags;Dell'Amico,1993
2. Computers and Intractability, a Guide to the Theory of NP-Completeness;Garey,1979
3. Optimisation and approximation in deterministic sequencing and scheduling: a survey;Graham;Ann. Discrete Math.,1979
4. Optimal two-and three-stage production schedules with setup times included;Johnson;Naval Res. Logist. Quart.,1954
5. E.L. Lawler, J.K. Lenstra, A.H.G. Rinnooy Kan and D.B. Shmoys, Sequencing and scheduling: algorithms and complexity, Centre for Mathematics and Computer Science, Report BS-R8909, The Netherlands.