Nintendo Power Final Fantasy strategy guide
This book was what got me into the insane obsession with FF in the first place. It was also helpful in making the walkthru.
How can I not thank Square?
The best FF1-only site out there. It inspired me to work hard on this site.
Final Fantasy Hackster
This program (along with FF Bytes) was very helpful in getting accurate info on everything.
JWPce, Merriam Webster Japanese-English Dictionary, Webster's New World Compact Japanese Dictionary, Random House Japanese-English English-Japanese Dictionary, Cassel's Latin & English Dictionary, The Merriam-Webster Dictionary
These dictionaries were all helpful in translating Japanese items, monsters, etc.
Advanced Dungeon's & Dragons 2nd Edition Monstrous Manual
This book was handy in translating things, and in providing info about monsters, since it turns out much of FF1 was borrowed from D&D.