LibreOffice Writer is a powerful text editor with a nice bibliography management. Yet, not very user-friendly. For example, if you want to insert a bibliography entry in a document, you are presented with a list that contains only the short name of the reference, making it difficult to use large databases. Moreover, each database entry must be manually inserted into the database.
But with the help of the bibliography manager JabRef, things get more simple. It uses the BibTex file format, so the bibliographical databases made with it are compatible with LaTeX. It has a nice online search tool which can populate a bibliography entry with all the information based on ISBN for books or document ID for different papers. And most important it integrates with LibreOffice and OpenOffice, allowing users to insert a bibliography entry with a simple two-click operation.