1. George E. Andrews and Bruce C. Berndt, Ramanujan’s lost notebook. Part IV. Springer, New York, 2013.
2. Andrew Granville, Smooth numbers: computational number theory and beyond. Algorithmic number theory: lattices, number fields, curves and cryptography, 267–323, Math. Sci. Res. Inst. Publ., vol. 44, Cambridge Univ. Press, Cambridge, 2008.
3. Charles Robert Hadlock, Field theory and its classical problems. Carus Mathematical Monographs, vol. 19. Mathematical Association of America, Washington, D.C., 1978.
4. Bernhard Hornfeck and Eduard Wirsing, Über die Häufigkeit vollkommener Zahlen. Math. Ann. 133 (1957), 431–438.
5. Neal Koblitz, p-adic numbers,
p-adic analysis, and zeta-functions. Second edition. Graduate Texts in Mathematics, vol. 58. Springer-Verlag, New York, 1984.