1. Hahn H: Convolution sums of some functions on divisors. Rocky Mt. J. Math. 2007, 37(5):1593-1622. 10.1216/rmjm/1194275937
2. Besge M: Extrait d’une lettre de M. Besge à M. Liouville. J. Math. Pures Appl. 1862, 7: 375-376.
3. Cheng N, Williams KS: Evaluation of some convolution sums involving the sum of divisors functions. Yokohama Math. J. 2005, 52: 39-57.
4. Lahiri DB:On Ramanujan’s function τ ( n ) and the divisor function σ ( n ) , I. Bull. Calcutta Math. Soc. 1946, 38: 193-206.
5. Melfi G: On some modular identities. In Number Theory. de Gruyter, Berlin; 1998:371-382. (Eger, 1996)