Cuzick, J. and Edwards, R. (1990). Spatial clustering for inhomogeneous populations (with discuss), Journal of the Royal Statistical Society, Series B, 52, 73-104.
Duczmal, L. and Assunc?o, R. (2004). A simulated annealing strategy for the detection of arbitrarily shaped spatial clusters, Computational Statistics & Data Analysis, 45, 269-286.