Final Fantasy VII/Literature and sources
The expression of "using the sources" is getting a bit vague in a walkthrough - most of the content for this is in the game itself. Most of the gameplay details can easily be figured out from the game itself. Numerical data... well, likewise figurable out from the game, and singular facts aren't even copyrightable, while specific representations and collections of such are.
Anyway, this isn't meant to be strict scholarly work - most of the stuff comes from the game anyway, and there isn't any point in pointing out where any individual facts and numbers have been looked up, be it the game or other walkthroughs. But this isn't meant to be wholesale copyright violation or self-glorification either - it's good courtesy to list what sources have been consulted.
So yes, following sources have been consulted, in no particular order, when composing this guide - please add any of yours if you happen to use them
- Final Fantasy VII Player's Manual (PC version).
- MacDonald, Chris ("Kao Megura"). FINAL FANTASY VII FAQ v2.2. 
- Adams, Nick. The Chocobo Manifesto. 
- Tiddles et al., Caves of Narshe. 
- O'Day, Steele. Final Fantasy 7 Universe.  (Great partial walkthrough with pictures)
- Shin-Ra.ru - Shin-Ra Electric Power Company. shinra.ru 
- Adams, Nick. The Chocobo Manifesto. (Available via gamefaqs.com, not linkable directly)
- Final Fantasy Finland. Gold Chocobon kasvatus. 
- BlueShinra's Final Fantasy Wiki.  This wikitext is also Directly appropriatable: "All original (textual) content on this site is copyright-free, and as such, can be altered or modified by anyone (don't take it personally ^_~)." Not that much FF7 content, but very helpful nevertheless.
- ff7_gal. FF7OSG: Sephiroth's HP.