The DSLR Observing Manual was a collective effort by a group of DSLR observers both new and experienced, and was created as part of the AAVSO's Citizen Sky initiative. The DSLR Observing Manual is a great read for those wanting to get started with DSLR observing, or wanting to put their cameras to better scientific use making variable star observations.
The Guide to CCD Photometry is a complete rewrite of the original CCD Observing Manual, and is designed to help CCD observers move forward to become CCD photometrists. This newly-written guide covers everything you need to know to put your CCD camera to good use making variable star measurements, and will help you maximize their usefulness with information about observation planning, signal-to-noise calculations, proper calibration techniques, and photometric transformations. It also provides you with information about why you're making variable star observations in addition to telling you how, to help you make better-informed decisions about what to observe and how.