2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/66703A hypergeometric identity equating a triple sum to a single sum, originally found by Gelfand, Graev and Retakh [Russian Math. Surveys 47 (1992), 1-88] by using systems of differential equations, is given hypergeometric proofs. As a bonus, several $q$-analogues can be derived.considerably revised and extended; more $q$-analogues are derived; in particular, a new section has been added with $q$-analogues which are not only valid formally but also analyticallyClassical Analysis and ODEs33C70 (Primary) 33C20 33D70 (Secondary)text