@article {31915,
	title = {Determination of the heterotrophic activity of epilithic microbial populations},
	volume = {Am. Soc. Test. Mater. Spec. Tech. Publ. 695},
	year = {1979},
	pages = {180-195},
	author = {Ladd, T. I. and Costerton, J. W. and Geesey, G. G.}
}
