1. de Bruijn, N.G., Erdős, P.: A colour problem for infinite graphs and a problem in the theory of relations. Indagationes Math. 13, 369–373 (1951)
2. Erdős, P.: Problem (p. 681); P. Erdős, Chairman, Unsolved Problems. In: Nash-Williams, C.St.J.A., Sheehan, J. (eds.) Proceedings of the Fifth British Combinatorial Conference 1975, University of Aberdeen, July 14–18, 1975, Congr. Numer. XV, Winnipeg, Utilitas Mathematica (1976)
3. Erdős, P.: Combinatorial problems in geometry and number theory. In: Relations between combinatorics and other parts of mathematics, Proc. Sympos. Pure Math., Ohio State Univ., Columbus Ohio (1978)
4. Proc. Sympos. Pure Math., XXXIV. American Mathematical Society, Providence, pp. 149-162 (1979)
5. Erdős, P.: Some applications of graph theory and combinatorial methods to number theory and geometry. Algebraic Methods in Graph Theory (Colloq. held in Szeged, Hungary 1978), Vol. I, Coll. Math Soc. J. Bolyai. 25, 137–148 (1981)