@article{1183422298, author = {Williams, K. P.}, title = {The asymptotic form of the function $\Psi \left( x \right)$}, journal = {Bull. Amer. Math. Soc.}, volume = {20}, number = {3}, year = {1913}, pages = { 472-479}, language = {en}, url = {http://dml.mathdoc.fr/item/1183422298} }
Williams, K. P. The asymptotic form of the function $\Psi \left( x \right)$. Bull. Amer. Math. Soc., Tome 20 (1913) no. 3, pp. 472-479. http://gdmltest.u-ga.fr/item/1183422298/