Making Call Numbers Work For You

A call number is like your home addresses. An address helps you find a specific house within a city; a call number helps you find the exact location of a book on the library shelf.

There are 2 basic parts to a call number:

Subject - This part is made up of all numbers, ranging from 3 to 10 or more digits (depending on how narrowly focused the topic of the book).

Author - This part begins with a letter that matches the first letter of the author's last name, followed by 2 or 3 numbers, and then usually another letter that matches the first word of the title.

For example, the call number for the book The Great Trek of the Russian Mennonites to Central Asia, 1880-1884, by Fred Richard Belk is


This diagram identifies the various parts of the call number.


The first line of this call number comes from the Dewey Decimal Classification system. Our library uses this system to organize all the books and other materials. Students in the United States are familiar with this system because it is used in most public and school libraries. (A librarian named Melvil Dewey devised this system in 1876 as a way to categorize all knowledge at that time. It has been revised 21 times since then to reflect additions to that knowledge, like space exploration, the Internet, etc.)

These are the 10 major divisions of the Dewey classification system. Under each major division are 10 subdivisions, to break down the broad topic areas into smaller topics. As you move your cursor over each section, you will see the kinds of sub-topics available under each broad division.

Go back to the 300s one more time to see the 10 subdivisions for the Social Sciences.

Now, if you pass your mouse over the image below, you will see how the 360s can be subdivided even more to focus in even closer on a more precise topic.

Many of the call numbers you see on books in our library have a decimal point after the first 3 numbers, followed by more numbers after the decimal. That's because the Dewey Decimal system allows you to continue subdividing the topic - by adding more digits - until you arrive at a number that precisely describes the topic of the book.

The 363s can be subdivided even more to show these topics.

That's how you come up with an outrageous number like 363.810962409049 for a book on the 1998 famine in Sudan. (It seems like the smallest books have the longest call numbers!)

So, what does this mean to you? Don't worry - you won't be expected to know all the call numbers of the books in the library! But if you understand a little bit about how the books are organized, you can go directly to the correct section of our collection and browse around until you find something on your topic.

This can be especially useful if you're still looking for a topic for a research paper you've been assigned. For example, if you want to research international economics, and you know that 330 is the number for economics, you can go to the 330s section of the library and browse around until you find a topic that interests you. It's like going to the store to buy some new clothes -- sometimes you don't know exactly what you want until you see it, but you can at least start looking in the right department!

You are at the end of Module 1!


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