These volumes offer a wealth of detail about the Beatles' American recordings and their first visit to the United States, touching on everything from contracts and lawsuits to promotional materials, all richly illustrated. Spizer's imprint, 498 Productions, refers to the catalog number of a Vee-Jay single on which the Beatles' name is misspelled (as Beattles). Information: beatle.net.

• "Complete Beatles Audio Guide," by Doug Sulpy (The 910, 2006).

The latest in a regularly updated series of bootleg guides, this volume points collectors to the best sources for every circulating (officially or otherwise) Beatles recording. Sulpy's imprint, The 910, refers to his quarterly bootleg review magazine, which in turn refers to the Beatles song "One After 909." Information: dougsulpy.com.

• "Eight Arms to Hold You: The Solo Beatles Compendium," by Chip Madinger and Mark Easter (44.1 Productions, 2000).

This is the place to look for information about the former Beatles' solo live and studio recordings, through 2000. A more comprehensive two-volume look at John Lennon and Yoko Ono's music, by Madinger and Scott Raile, is planned for October 2007. The imprint, 44.1, is the sampling rate of the digital waveform on a CD. Information: 8-arms.com and lennonstrangedays.com