LCCN Permalink is a service provided by the Library of Congress that allows one to generate links to items in the LC collection by the Library of Congress Control Number (LCCN). The format is:
This is similar to the following examples of direct links used in other online catalogs such as ISBN Linking in WorldCat and ISSN linking in my own workplace’s catalog. These can be used to create stable, static links to items in catalogs, and are therefore very helpful for citing items online.
found via Web4lib