Open access publishing of monographs may be possible, but it is however still rare compared to open access journal articles. Some publishers (e.g. Springer, de Gruyter) have an option for gold open access, but the book processing charge (BPC) may be considerably higher than the APC for journal articles. The business models for open access publishing of books are still not as established as for journal articles.
OA publishing of monographs University of Jyväskylä
Guide for open access publishing of monographs for arts, humanities and social science researchers, JISC, UK.
Directory of open access books (DOAB), also sorted by topic.
OAPEN Library OA books, mainly humanities and social sciences.
OpenEdition brings together four platforms dedicated to electronic resources in the humanities and social sciences.
Monographs mainly in social sciences and humanities. Information for authors.
JSTOR - more than 9,000 open access books.
Books are made open access on MUSE through a variety of funding initiatives, including Knowledge Unlatched, NEH Humanities Open Book grants, TOME, and individual publisher programs.