 Netherlands, 1977.

| Chang, C.C. &amp; Keisler, H.J.,
|'Model Theory',
| North-Holland, Amsterdam, NL, 1973.

| Chang, Chin-Liang &amp; Lee, Richard Char-Tung,
|'Symbolic Logic and Mechanical Theorem Proving',
| Academic Press, New York, NY, 1973.

| Crossley, J.N., et al.,
|'What Is Mathematical Logic',
| Oxford University Press, Oxford UK, 1972.

| van Dalen, Dirk,
|'Logic and Structure', Second Edition,
| Springer-Verlag, Berlin, Germany, 1983.

| Dijkstra, Edsger W. &amp; Scholten, Carel S.,
|'Predica