“…In order to obtain fundamental soliton solutions, we expand functions g(r, z) and f (r, z) as power series of a formal expansion parameter , and truncate g(r, z) as g(r, z) = g 1 (r, z) and f (r, z) as f (r, z) = 1 + 2 f 2 (r, z) [25]. Inserting these expressions into Eqs.…”