Reduction of the self-dual Yang-Mills equations. I. The Poincaré group

by Zhdanov, R.Z., Lahno, V.I., Fushchych, W.I.
Published 1995

Separation of variables in the two-dimensional wave equation with potential

by Zhdanov, R.Z., Revenko, I.V., Fushchych, W.I.
Published 1994