On cases for which the formula x4+mxxyy+y4 can be reduced to a square
Euler first dismisses the obvious cases when x=y and m=2 or when one of the values is zero. Then he goes on to solve the problem, finding about 90 values of m less than 200 for which solutions exist (section 13). He closes with a "more elegant solution."
Original Source Citation
Mémoires de l'académie des sciences de St.-Petersbourg, Volume 7, pp. 10-22.
Opera Omnia Citation
Series 1, Volume 5, pp.35-47.