Claims

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1966_01_01_erdos_renyi_sos: Erdős, Rényi and Sós prove that the largest number of edges of a graph on n vertices with no four-cycle is asymptotic to n^{3/2}/2, the formula Problem 765 asks for; refereed in Studia Sci. Math. Hungar. 1 (1966); Lean linked.

1966_08_01_brown: Brown proves, independently of Erdős, Rényi and Sós, that the largest number of edges of a graph on n vertices with no four-cycle is asymptotic to n^{3/2}/2; Section 3 of a refereed paper in Canad. Math. Bull. 9 (1966).

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