[1]
J. Mishew and E. Khristov, “ON AN APPLICATION OF THE OPERATORS OF CRUMM-ICAEIN TO THE DECOMPOSITION IN PRODUCTS OF THE SOLUTIONS OF TWO EQUATIONS OF SCHRODINGER WITH EQUAL SPECTRA”, Ann. Sofia Univ. Fac. Math. and Inf., vol. 82, no. 2, pp. 219–247, Dec. 1991.