[[1] BROMWICH, T. J. I’A.: An Introduction to the Theory of Infinite Series (3rd ed.), Chelsea, New York, NY, 1991.]Search in Google Scholar
[[2] FICHTENHOLZ, G. M.: Differential- und Integralrechnung, 14. Aufgabe, H. Deutsch, Frankfurt am Main, 1999.]Search in Google Scholar
[[3] KNOPP, K.: Theory and Application of Infinite Series (2nd. ed.), Blackie & Son, Ltd., London, 1964.]Search in Google Scholar
[[4] PRUS-WI´SNIOWSKI, F.: A refinement of Raabe’s test, Amer. Math. Monthly 115 (2008), 249-252.10.1080/00029890.2008.11920522]Search in Google Scholar
[[5] VOROBEV, N. N.: Teoria Riadov, Nauka, Moskva, 1975. (In Russian)]Search in Google Scholar