These databases provide extensive coverage of architecture:
These databases cover multiple subjects including architecture:
The RIBA Architectural Publications Index is now part of the online RIBA Library Catalogue, an internationally recognized resource for architecture research.
A Google Scholar search produces results from books and academic/peer-reviewed journals.
Searching from home? Make sure to add University of Illinois at Chicago as your library so that you can connect to the library's electronic journals for free. This can be done under Scholar Preferences-->Library Links.