CONFLUENT HYPERGEOMETRIC FUNCTIONS OF MANY VARIABLES AND THEIR APPLICATION TO THE FINDING OF FUNDAMENTAL SOLUTIONS OF THE GENERALIZED HELMHOLTZ EQUATION WITH SINGULAR COEFFICIENTS - URINOV, Ahmadzhon Kushakovich; ERGASHEV, Tuhtasin Gulamzhanovich (Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, 2018)