Are you asking about citing the System Reference Document in your Section 15? To take it from the top:
Download, read, parse, and internalize the terms of the Open Game License. That document contains a number of legal obligations: things you *must* and *must not* do in order to legally publish an OGL game supplement. In return for following the rules, you are allowed to freely use the System Reference Document and any Open Game Content published under the OGL.
You may want to grab an OGL publication of some kind so that you can see the OGL "in action," as it were. Even free documents are expected to comply with the OGL, which includes having the required OGL text.
The System Reference Document is not, strictly speaking, embodied in a book (although at least one publisher IIRC took large portions of the SRD and published them -- this was and is perfectly legal according to the OGL). It is, however, available online for free at the links shown above. When you find yourself writing game elements into your work, double-check to see they either (1) can be found in the SRD (WARNING: some things in even the core books are not in the SRD), (2) are entirely original to you (WARNING: this means "entirely," not "kind of"), or (3) are Open Game Content already (WARNING: remember to cite the book you use: publishers have gotten in trouble in the past for messing up Section 15 -- and if you don't know what I mean by Section 15, it's time to reread the OGL).
For example, if you find yourself in need of one of the feats or classes from the 3.5 PHB II, you'll find that book is off limits, and you'll have to make do with something else. If you find yourself in need of the affiliation rules from the 3.5 DMG II, you'll find that book is also off limits, and you'll again have to make do with something else. If you find yourself in need of a scorpionfolk from the 3.5 MM II, good news, that's OGC, and you're okay.
[EDIT] If, OTOH, you're asking whether you can say the reader should have his Player's Handbook and Dungeon Master's Guide handy, no, you may not say that. One of the provisions of the OGL is that you can't use anybody's trademarks, even to indicate compatibility, without their permission. You see now, I hope, how important completely understanding it is. [/EDIT]
HTH. HAND.