The Reversion of Class Number Relations and the Total Representation of Integers as Sums of Squares or Triangular Numbers
Eric Temple Bell · Annals of Mathematics · 1921
E. T. Bell, The Reversion of Class Number Relations and the Total Representation of Integers as Sums of Squares or Triangular Numbers, Annals of Mathematics, Second Series, Vol. 23, No. 1 (Sep., 1921), pp. 56-67