1. Progress in Maths;D Bertrand,1981
2. Beukers F, Irrationality proofs using modular forms,Soc. Math. de France, Astérisque 147–148 (1987), pp. 271–283.
3. Kohnen W and Zagier D, Modular forms with rational periods, in:Modular Forms (ed. R A Rankin) pp. 197–249, (Chichester: Ellis Horwood) 1984.