@article {BermanDiggle1989JRSS,
	title = {{Estimating weighted integrals of the second-order intensity of a spatial point process}},
	journal = {Journal of the Royal Statistical Society B},
	volume = {51},
	year = {1989},
	pages = {81-92},
	author = {Berman, M. and Diggle, P.~J.}
}