MP3Pro Soft
- Features software and information about mp3PRO and other similar audio formats.
- http://mp3pro-soft.narod.ru/e_index.html

MP3 Tech
- Source of detailed technical information about audio encoding with MP3 and similar formats. Features documentation, articles, source code and a message board for programmers.
- http://www.mp3-tech.org/

ID3v2
- Description of ID3 tagging standard (version 2) for MP3 files. Includes specifications, implementations and a mailing list.
- http://www.id3.org/

MP3-O-Phono
- A custom made MP3-player device. Site contains many implementation details as well as photos.
- http://www.softlab.ece.ntua.gr/~sivann/mp3ophono/

MPEG Audio Frame Header
- Technical explanation of how MPEG audio files and their headers are constructed.
- http://www.dv.co.yu/mpgscript/mpeghdr.htm

Fraunhofer IIS: MP3
- Features history and technical information about the MP3 format.
- http://www.iis.fhg.de/amm/techinf/layer3/

MP3licensing.com
- Details of the MP3 licensing programs for Thomson Multimedia and Fraunhofer IIS-A.
- http://www.mp3licensing.com/