On imprimitive multiplicity-free permutation groups the degree of which is the product of two distinct primes.

Mitsugu Hirasaka On imprimitive multiplicity-free permutation groups the degree of which is the product of two distinct primes. 30-38 2009 30 Eur. J. Comb. 1 http://dx.doi.org/10.1016/j.ejc.2008.03.001 db/journals/ejc/ejc30.html#Hirasaka09