P. Nielsen

Oxygen, organic matter, and sediment granulometry as controls on hyporheic animal communities
Strayer, David L., S.E. May, P. Nielsen, W. Wollheim, and S. Hausam. 1997. “Oxygen, Organic Matter, And Sediment Granulometry As Controls On Hyporheic Animal Communities”. Arch. Hydrobiol. 140: 131-144.
An endemic groundwater fauna in unglaciated eastern North America
Strayer, David L., S.E. May, P. Nielsen, W. Wollheim, and S. Hausam. 1995. “An Endemic Groundwater Fauna In Unglaciated Eastern North America”. Can. J. Zool. 73: 502-508.