  A class of one-relator groups such that every group in the class is
determined by a triple of integers and is an HNN-extension of some Baumslag --
Solitar group is considered. A criterion for two groups in this class to be
isomorphic and criterion for two non-isomorphic groups to be a homomorphic
image of each other are obtained. This result leads to a negative answer to the
question 3.33 from "Kourovka Notebook".
