1. W. E. Bull "Time tense and the verb " University of California Publications in Linguistics Vol. 19 (1960). W. E. Bull "Time tense and the verb " University of California Publications in Linguistics Vol. 19 (1960).
2. B. Langefors "Theoretical analysis of information systems " Studentlitteratur Auerbach Lund Sweden (1966). B. Langefors " Theoretical analysis of information systems " Studentlitteratur Auerbach Lund Sweden (1966).
3. R. Mattison "A formal system for the logical analysis of temporal relationships between intervals of time " Memo. RM-5279-PR Rand Corporation Santa Monica CA (April 1967). R. Mattison "A formal system for the logical analysis of temporal relationships between intervals of time " Memo. RM-5279-PR Rand Corporation Santa Monica CA (April 1967).
4. A. Prior Past present future Oxford University Press (1967). A. Prior Past present future Oxford University Press (1967).
5. R. Mattison "An introduction to the model theory of first-order predicate logic and a related temporal logic " Memo. RM-5580-1-PR Rand Corporation Santa Monica CA (June 1969). R. Mattison "An introduction to the model theory of first-order predicate logic and a related temporal logic " Memo. RM-5580-1-PR Rand Corporation Santa Monica CA (June 1969).