Oriental Institute, University of Chicago (Art/Symbolism Only)
Books & Articles Available to Download From The University of Memphis
Sources from the Netherlands Institute for the Near East / Nederlands Instituut voor het Nabije Oosten (NINO)
This one is a bit tricky, as most of the sources are in Dutch/German/French.
Sources from the Czech Institute of Egyptology
Despite the dual titles on a lot of the files, the majority of the books from the English language site are in English (they warn you if it is in Czech).
MFA Boston’s Complete Giza Digital Library
This is the complete corpus of publications from the MFA’s work on the Giza Plateau, available as downloadable pdfs. http://www.gizapyramids.org/static/html/authors_list.jsp
Books available to download from the Metropolitan Museum of Art
In terms of your paper research, you should have a look at the Met’s bulletins & online journal editions, to see if your object/object time is mentioned.