Randolphs Robot Game is NP-hard! - Birgit Engels; Tom Kamphans (Electron. Notes Discret. Math., 2006)

Integer Flow with Multipliers: The Special Case of Multipliers 1 and 2. - Birgit Engels; Sven Oliver Krumke; Rainer Schrader; Christiane Zeck (CTW, 2009)

The Transitive Minimum Manhattan Subnetwork Problem in 3 dimensions. - Birgit Engels (Discret. Appl. Math., 2010)

A Generalized Network Model for Freight Car Distribution. - Birgit Engels (2011)

Freight car dispatching with generalized flows. - Birgit Engels; Rainer Schrader (Networks, 2015)