P. Erdös

发表

V. T. Sós, A. Meir, V. Sós, 1972, Canadian Mathematical Bulletin.

P. Erdös, 1964, Canadian Mathematical Bulletin.

Richard Mollin, P. J. Cameron, P. Erdös, 1990 .

J. W. Moon, P. Erdös, 1964, Canadian Mathematical Bulletin.