1. H. Freudenthal, The Language of Logic (Elsevier, Amsterdam, 1966).
2. A. Church, Introduction to Mathematical Logic (Princeton Univ. Press, Princeton, N.J., 1956), Vol. 1.
3. E. Mendelson, Introduction to Mathematical Logic (Van Nostrand, Princeton, N.J., 1963).
4. K. Gosztonyi, “The ’new math’ reform and pedagogical flows in Hungarian and French mathematics education,” Ninth Congress of the European Society for Research in Mathematics Education (CERME 9), Faculty of Education Charles University in Prague, February 2015 (ERME, Prague, 2015), pp. 1709–1716.
https://hal.archives-ouvertes.fr/hal-01288002. Accessed December 21, 2022.
5. A. P. Ershov, A. G. Kushnirenko, G. V. Lebedev, A. L. Semenov, and A. Kh. Shen, Fundamentals of Informatics and Computer Science: A Trial Textbook for Secondary Educational Institutions, Ed. by A. P. Ershov (Prosveshchenie, Moscow, 1988) [in Russian].