Steinitz classes of metacyclic extensions

Let G be a metacyclic group of order pq, where p and q are distinct odd prime numbers, let N\k be a Galois extension whose Galois group G(N\k) is isomorphic to G. Let R-N, R-k be the rings of integers of N and k. As R-k-module R-N is completely determined by [N: k] and by its class in the class group of R-k. The paper determines the classes realized by tame Galois extensions N\k with G(N\k) congruent to G and proves that they form a group.