  This is a historical note. In 1981 we constructed a discrete version of
quantum nonlinear Schroedinger equation. This led to our discovery of quantum
determinant: it appeared in construction of anti-pod (11). Later these became
important in quantum groups: it describes the center of Yang-Baxter algebra.
Our paper was published in Doklady Akademii Nauk vol 259, page 76 (July l981)
in Russian language.
