How to make one reference to multiple citations

I'd like to do following thing. In my text I want to refer to citations with

\cite{ref1}


and in the reference section under this reference, e.g. [1] there should be sth. as follows:

[1] (a) author1, author2, ..., journal1, vol1, pp1 year1, (b) author3, author4, ..., journal2, vol2, pp2, year2 (c) and so on

It is not the question about the style of the reference, but how to make many references (a), (b), (c) under one citation [1]?

biblatex/biber supports fixed sets (@set in the bib) and dynamic sets:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[subentry]{biblatex}