Grove Art Online is an encyclopedia within Oxford Art Online that includes excellent articles accompanied by lists of recommended readings and links to external resources such as images of works in museum collections.
This encyclopedia contains an article on Buddhism as well as articles on specific sites and monuments (such as Ayutthaya) or building types (such as stupa) and articles about the art and architecture of specific countries and regions, iconography and subject-matter, and more.
The article on the Indian Sub-Continent includes a useful section on Buddhist Iconography and Subject-Matter, with sections on:
The article on Central Asia includes sections on Buddhist iconography and Buddhism and links to important Buddhist sites and to information about patronage.
The article on South-east Asia includes links to important sites and a section on State and Religious patronage.
The article on China includes a discussion of Buddhism in the Religion and Philosophy section as well as well as information on Buddhist religious buildings, Buddhist sculpture, Buddhist themes in painting, and more.
The article on Japan includes a section on Buddhist Religion and Iconography, with sub-sections on varieties of Buddhism:
The Japan article also includes information about Zen Buddhist masters in its Calligraphy section and sub-sections about Buddhist painting, Buddhist sculpture, and Buddhist architecture, including Buddhist temple precincts.
The Sri Lanka article also includes a section on Buddhism as well as information about monasteries, shrines, and other important Buddhist sites.
Dictionaries of Buddhist iconography:
In addition to the Article Databases listed on the separate tab, consult these databases and indexes to locate articles on Buddhist art and architecture:
Try searching the UCLA Library Catalog under these subjects (most can also subdivide by country, region, or by subtopics):
You may need to place your works in historical context. Consider consulting country and period surveys such as: