arxiv ref: 1407.7832Title: Non-planar Feynman integrals, Mellin-Barnes representations, multiple sumsAuthors: J. Bluemlein, I. Dubovyk, J. Gluza, M. Ochman, C. G. Raab, T. Riemann, C. SchneiderNode: DESYSupervisor: Bluemlein