Don’t buy DRM-encumbered ebooks from Google.
But do download public domain ePub and PDF versions of old books on art and art history from them.
Works of art and artists in England
The art of drawing in perspective
Precepts and observations on the art of colouring in landscape painting
Catalogue / American Art Association, Anderson Galleries, inc., New York
The Italian schools of painting
A biographical history of the fine arts
And do look in the “Related Books” recommendations at the bottom of each page.