I'm starting a library of texts of worker cooperatives on the website, with the intent that people can read and comment on texts.  I'm going to try to start with more recent digitally available articles, since there hasn't been a lot printed in book form on the subject since the 1990s, but I wanted to pitch three great slightly older books that can be helpful if you are just getting to know the movement and looking for a little context.  

• When Workers Decide: Workplace Democracy Takes Root in North America (1992)
• Worker Cooperatives in America (1984)
• Workplace Democracy and Social Change (1982)

What's great about these books from an introductory perspective is that they are compilations of short essays, so they have a lot of voices and perspectives, including practitioners, activists, and academics.  The shortness of the essays is also nice for a newcomer to jump around and get a quick sense of what was going on.  I wish there was a such a book written for the contemporary situation.   Maybe a best of GEO will come out once every few years now that their newsletter has gone digital.

There are also a few other book lists out there of note.  The U.S. Federation of Worker Cooperatives has organized a Worker Co-op & Economic Democracy Reading List at Goodreads which, as the title implies, includes titles more broadly about economic democracy.  There is also a bibliography on worker cooperatives at the nascent website goodsocietynow.org.  Of course every good book has a branching list of leads.  If you know of a good list, please feel free to leave it in the comments.