  Theoretycal results on the magnetization and susceptibility of a Heisenberg
diluted antiferromagnet in the square lattice are given. The models considered
have two exchange constants (J1-J2 and J1-J3) of which the second is much
smaller than the first (lopsided models). Cluster statistics for clusters with
up to 5 spins is given. A procedure to account for the contribution to the
magnetization of clusters with more than 5 spins is described.
