Dynamics of anti-dark and dark solitons in (2 + 1)-dimensional generalized, nonlinear Schrödinger equation - Nistazakis, H.E.; Frantzeskakis, DJ; Balourdos, PS; Tsigopoulos, A.; Malomed, B. A. (Physics Letters, Section A: General, Atomic and Solid State Physics, 2000)