@techreport{FuegenschuhHumpola2013, author = {Armin F{\"u}genschuh and Jesco Humpola}, title = {A Unified View on Relaxations for a Nonlinear Network Flow Problem}, institution = {ZIB}, address = {Takustr. 7, 14195 Berlin}, number = {13-31}, language = {eng}, year = {2013} }