Alla's is great for this kind of information.
Although if you would like it at hand in game, might I suggest something like Ackis?
you open your leatherworking up and hit the scan button. This will pull up a list of what you don't have in order of skill, click on the pattern and usually you can get an idea where to get it.
For more detailed information on securing the pattern this is the place to come. (by searching alla)
good luck.
Google: Wow curse ackis addon
that should be very specific enough to give you the link you need.
good luck.
(this site is full of information, I invite you to do some exploring)
--Beulah
edit: well obviously wowhead and others are great too! but since you are here ... :) I've used alla's for so long its crazy.
Edited, Feb 19th 2009 2:33pm by darkmoss