Here are links to useful resources for catalogers.
Dewey DecimalLibrary of Congress: http://catalog.loc.gov/ this is the cataloge site you can also get to the authoritiesauthorities, where you can locate marc record information pertaining to subject headings, link in the upper right corner or go to http://authorities.loc.gov/Dublin CoreOther Cataloging Systems: http://www.oclc.org/bibformats/en/ OCLC has a great site for checking those bib formats (knowing what information to put where in the bib) it also gives all the tag information and you don't have to be a member to get to this site. Audio-visual Materials
The On-Line Audiovisual Catalogers have just published a new 74-page guide entitled "Cataloging DVD and Blu-ray Discs Using AACR2 and MARC 21". Check it and their other useful resources out here.