The Library uses the Library of Congress classification system. If you're not familiar with LC call numbers, they can seem a little confusing, but don't worry: here's a quick explanation of how they work.

Books are arranged first **alphabetically**, using the letters at the start of the call number: |
**LC**487 .C43 1994 |

Then **numerically**, by the numbers that come directly after the letter. These are read as **whole numbers**: in other words, 400 comes later than 43. |
LC**487** .C43 1994 |

Then **alphabetically** again, by the letter that comes after the decimal point: |
LC487 .**C**43 1994 |

Then **numerically** again, by the number that comes directly after that letter. These are read as **decimal numbers**: in other words: 55 comes later than 541. |
LC487 .C**43** 1994 |

There may be another letter-number combination after the one with the decimal point in front of it. If so, you read it the same way: first alphabetically by letter, and then numerically in decimal order. |
BX1795 .I57 **E83** 2000 |

The four-digit number at the end of the call number is the publication date of the item. |
LC487 .C43 **1994** |

If you want to learn about which subjects are associated with which Library of Congress call numbers, see the Library of Congress Classification Outline.