“…In this connection, one can find the H 1 -integral interesting not as being an alternative tool for integration, with some advantages over other integration processes, but as producing the class of H 1 -integrable functions with its relations to other classes of functions. A few important results have been received in the latter direction, but, it seems, some investigation opportunities remain, especially those related to characterizations of classes generated by some arithmetic operations with H 1 -integrable functions as one of the arguments (for a sample problem see [12,Question 2.3]).…”