Oevel, Gudrun, et al. “Action-Angle Representation of Multisolitons by Potentials of Mastersymmetries.” Prog. Theor. Phys., vol. 83, 1990, pp. 395–413.

Oevel, Gudrun. Reduktion integrabler Systeme auf ihre Multisoliton Mannigfaltigkeiten. 1990.

Fuchssteiner, Benno, and Gudrun Oevel. “Geometry and Action-Angle Variables of Multi Soliton Systems.” Rev. Math. Phys., no. 1, 1989, pp. 415–79.