C. W. Trigg, C. W. Dodge and L. F. Meyers,
Comments on Problem 133,
Eureka (now Crux Mathematicorum) 2,
no. 7 (August--September 1976) 144--150.
Problem 133 is the problem, proposed by
K. S. Williams, who said he was shown it by one of his
C. W. Trigg gives a good history of the problem.