We're happy to report that, between then and now, the number of free texts has grown to 109. Published between 1937 and 1999, the art books/catalogues offer an intellectual and visual introduction to the work of Alexander Calder, Edvard Munch, Francis Bacon, Gustav Klimt & Egon Schiele, Fernand Léger, and Kandinsky. Plus there are other texts (e.g., Masterpieces of Modern Art and Abstract Expressionists Imagists) that tackle meta movements and themes.
Anyone interested in the history of the Guggenheim will want to spend time with a collection called "The Syllabus." It contains five books by Hilla Rebay, the museum's first director and curator. Together, they let you take a close look at the art originally housed in the Guggenheim when the museum first opened its doors in 1939.
To read any of these 109 free art books, you will just need to follow these simple instructions. 1.) Select a text from the collection. 2.) Click the "Read Catalogue Online" button. 3.) Start reading the book in the pop-up browser, and use the controls at the very bottom of the pop-up browser to move through the book. 4.) If you have any problems accessing these texts, you can find alternate versions on Archive.org.
You can find many more free art books from the Getty and the Met below.