Complete Sinawali by Rey Galang describes about two dozen "Sinawali" or double stick drills as done by the Bakbakban group in New Jersey. The sinawali patterns described here are not the usual symmetrical patterns that most beginners are used to, and careful attention should be paid to the footwork, which allows the practitioner to perform the strikes with the proper distancing, timing, speed, and power to make them effective.
Bakbakban offers a videotape series that features some of their double stick patterns and there is usually a seminar once a year based on these as well. I would recommend attending a seminar after I had purchased the book and video in order to fine-tune the body-mechanics that are presented therein. All in all, an excellent book that belongs on the shelf of any Filipino martial artist.