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2. K. Jensen & N. Wirth 'Pascal user manual and report' Springer Verlag 1975. K. Jensen & N. Wirth 'Pascal user manual and report' Springer Verlag 1975.
3. R. F. Keller 'On Control Constructs for Constructing Programs' Sigplan Notices Vol 12 No 9 Sept 77 p 36. 10.1145/954604.954606 R. F. Keller 'On Control Constructs for Constructing Programs' Sigplan Notices Vol 12 No 9 Sept 77 p 36. 10.1145/954604.954606
4. E. W. Dijkstra 'Guarded Commands Nondeterminancy and Formal Derivation of Programs' CACM Vol 18 No 8 August 75 p 453. 10.1145/360933.360975 E. W. Dijkstra 'Guarded Commands Nondeterminancy and Formal Derivation of Programs' CACM Vol 18 No 8 August 75 p 453. 10.1145/360933.360975
5. D. F. Hendry & B. Mohan 'A BCL Manual' University of London I.C.S. 1968. D. F. Hendry & B. Mohan 'A BCL Manual' University of London I.C.S. 1968.