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. 1991;82(2):219-247. Accessed December 17, 2025. https://annual.uni-sofia.bg/index.php/fmi/article/view/545