@article {urfer2001measurement,
	title = {Measurement of biomass activity in drinking water biofilters using a respirometric method},
	journal = {Water research},
	volume = {35},
	number = {6},
	year = {2001},
	pages = {1469{\textendash}1477},
	publisher = {Pergamon},
	author = {Urfer, Daniel and Huck, Peter M}
}
