"Secondary sources are those which are written ABOUT events in the past. They usually interpret those events through the lens of the time period in which they are written. New discoveries are made and attitudes change over time causing understandings of past events to change. Facts may remain consistent, but interpretations change, sometimes drastically. 

Secondary sources may address the primary source, but were created later by someone who did not experience it first-hand or participate in the events or conditions you’re researching. Scholars writing about historical events, people, objects, or ideas produce secondary sources because they help explain new or different positions and ideas about primary sources. These secondary sources generally scholarly books, including textbooks, articles, encyclopedias, and anthologies.

Sources that have been published very recently will reflect the current theories and understanding of the past. If you use a secondary source that was published decades ago, it is important to know what subsequent scholars have written on the topic and what criticism they have made about the earlier work or its approach to the topic." 

From: Primary and Secondary Sources: ABOUT, Otis College of Art & Design

In the field of Art History, much of the literature is published in different languages, although English is predominant. You are encourage to investigate scholarly book in ALL languages, as you can glean a great deal of  important information from them:.

Search for books using the search box below

• You can select to search particular fields using the dropdown menu below (Title, Author, Subject, Call Number) or leave it set to "Anywhere" to search all fields.
• Narrow to online resources on the search results page by marking "Online" checkbox on the left side. 

Be aware that you cannot use Quotation marks (e.g., "Illuminated Manuscripts" ) or an Asterisk * ( e.g., architect*  = architect, architects, architecture, architectural )  with this search tool. Instead visit the UofT Libraries Website onesearch.library.utoronto.ca