1.Zolotarev, V.M.
Some inequalities in probability theory and their application in sharpening the Lyapunov theorem.
Soviet Math. Dok. 8, 1427-1430 (1967).
2.Esseen, C.G.
A  moment  inequality with  an  application  to  the  central  limit  theorem.
Skand. Aktuarietidskr. 39,  160-170  (1956).