the library can be.
I went to the library hoping to find some nissan repair manuals
and found out that their computers have free use to ALLDATA online.

I didnt know what Alldata was untill I went to there website.
The site told me exactly where the camshaft sensors are located and
details on how to replace them. ALSO gave me code definitions, part
numbers, TSB's relating to camshaft sensors and vin numbers related
to the TSB's.

Anyway if your local library is online and has Alldata link check it out
for repair questions, TSB's w/complete definitions, Trouble codes, wiring
diagrams and I'm sure plenty more all free except the 1.20 print fee.