A one-stop source about accessory dwelling units, multigenerational homes, laneway houses, ADUs, granny flats, in-law units…
One of our editors (Martin) has created an open database of references about formal research into ADUs, other space-efficient forms of housing, and related topics such as demographics and environmental impact. Search it at this Zotero.org page: Space-Efficient Housing bibliography.
Martin welcomes new contributors to the database — contact him through the Zotero page or via a comment below.
We also maintain a wiki-like list of current municipal codes and regulations here.