If you are serious about stretching and flexibility you really need to read Stretching Scientifically by Thomas Kurz. It contains all the background information you need to know, along with stretching programs to increase your flexibility in the shortest possible time using the safest techniques. The Thomas Kurz book and other books of interest are displayed below.

You can read free articles by Thomas Kurz here:

Many of the techniques discussed in the Thomas Kurz book are also discussed in this document:

The following links may also provide some useful information: