Meškauskas, T., and F. Ivanauskas. “Initial Boundary-Value Problems for Derivative Nonlinear Schroedinger Equation. Justification of Two-Step Algorithm”. Nonlinear Analysis: Modelling and Control, vol. 7, no. 2, Dec. 2002, pp. 69-104, https://doi.org/10.15388/NA.2002.7.2.15195.