Loose leaf services are publications which collect materials that are published on a regular basis, usually monthly, bi-monthly, or every other month.  There are two ways loose-leafs can be organized:

• Cumulative:  This means that the material is collected, the new material being placed in the binder behind the older material.  Examples include the Environment Reporter (above), Criminal Law Reporter, and U.S. Law Week (below).
• Replacement:  This means that the material which is received replaces the material contained in the binder (usually individual pages replace individual pages, not whole sections).  Examples include some state statutes which may come in loose leaf form or administrative regulations.