  Software, and software source code in particular, is widely used in modern
research. It must be properly archived, referenced, described and cited in
order to build a stable and long lasting corpus of scientic knowledge. In this
article we show how the Software Heritage universal source code archive
provides a means to fully address the first two concerns, by archiving
seamlessly all publicly available software source code, and by providing
intrinsic persistent identifiers that allow to reference it at various
granularities in a way that is at the same time convenient and effective. We
call upon the research community to adopt widely this approach.
