Posted by: bluesyemre | April 28, 2019

The #OnlineBooks Page by #UniversityofPennsylvania Libraries


Books in a library are usually shelved by their call number, which arranges books by their main topic. Because of this, books with similar main topics will often appear near each other when you browse, allowing you to find multiple books on a subject that interests you.

Similarly, we also provide virtual shelves for online books filed by their Library of Congress call numbers. (This and the Dewey Decimal system are the most common call number schemes used. Dewey is more commonly used in public libraries; Library of Congress is more commonly used in larger research libraries in the US, and a similar system is also used in Canada.) Library of Congress “call numbers” actually start with letters, each of which represents a different topical area.

To start browsing, select a link below for the topical area that interests you. If you click on an “Overview” link, you will also see some of the more specific topics in that area that are represented by call numbers starting with two or three letters. For more detailed breakdown (but without links to online books) see the Library of Congress Classification Outline, or the very detailed full Library of Congress Classification.


Most of our books have call numbers and subject terms, but a small portion of them (about 1/6 at present) do not have call numbers, and a lot of our fiction books (and some of our more obscure nonfiction) do not have subject headings. Rare books, children’s books, and old popular fiction that’s no longer popular are more likely not to have a these things, compared to other kinds of books. You can look for books without call numbers or subject terms in our author and title listings, however.

In physical libraries, books have only one call number, which determines where they get shelved. In theory, it should be possible to assign multiple call numbers to online books, so that they can be found under multiple topics in the “virtual shelves”. As a practical matter, though, we can only support one call number per book at present. We try to choose ones that put books in their most relevant category. For more precise categorization, try our subject term browsing.

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