https://www.un.org/development/desa/indigenouspeoples/publications/desktop-publications.html
The United Nations Indigenous Peoples resource page is the most extensive single database I have found yet. It features a massive “compilation of all available guidelines, books, studies, reports, articles, training materials and documentation on indigenous peoples from the UN system and relevant entities.” While I could hardly begin to read all of the content that is link on this page, I can say that many of the books have direct links to PDFs and several of the publications are available in multiple languages. There is also a section labelled Policies and Guidelines which provide a variety of approaches to dealing with issues such as poverty and intellectual property. There are even links to purpose built tool kits and webinars on on topics such as land rights. The website provide a link to hundreds of documents covering a very wide variety of issues and topics.