1. Zur Arithmetik hyperkomplexer Zahlen;Artin;Hamb. Abh.,1928
2. Hecke operators on Γ0(m);Atkin;Math. Ann.,1970
3. A. O. L. Atkin and D. J. Tingley, Lecture Notes in Mathematics No. 476, pp. 135–141, Springer-Verlag, Berlin/New York, Table 5.
4. Twists of newforms and pseudo-eigenvalues of W-operators;Atkin;Invent. Math.,1978
5. Algorithm 287, matrix triangulation with integer arithmetic;Blankinship;Comm. A.C.M.,1966