Lee's manual is a good starting point.

Lyman's is a good one, as are the Hodgdon and Alliant websites. I use quite a few Hornady bullets and thus their manual is a good reference for me. Whenever starting to load a for a new caliber or set of components I like to have three or more sources of reference to give me a good place to start. Never do I use only one source unless I am already quite familiar with the caliber and/or components. Lee does no loading and testing of components as their manuals are a compilation of other manuals.

I use Lyman as a main source,but always cross reference because there can be a printing mistake.The manuals aren't going to give you your exact load as far as component makeup,so referencing the bullet and powder manufacturer verifies info.Adhere to notes also.As an example,Lyman notes use of Federal cases for a reason,they are thick like Starline and can hold pressure a little better in autos than Remington brass will.Primers are also a concern,just changing from a std to a magnum primer can increase pressure with one powder in a case where it really won't affect another much.

That's the reason you always start at the bottom and work up,what I can run for max in my gun may be over pressure in your same gun.The powder you use,different lots of the same powder,variations in crimp and OAL,and chamber specs can take a known good load and push it to have pressure signs.If you aren't near max there's some fudge room,but always back off when changing any component or lot when playing at max.Even 2 bullets the same weight with different profiles can vary the max charge to be safe.A 200gr LSW in 45acp is that way in one of my Lyman books.

Modern reloading, 2nd Edition (Lee). It's a compilation of a variety of sources. As one of the less expensive ones it's a decent choice. However, it lacks detail found in other places.
Lyman's 49th Edition Reloading handbook. Very good manual. Covers most things pretty well.
Another source of data compiled from various sources: Store
Web sites:
Load Data « Accurate Powders
Alliant Powder - Reloader's Guide
Cartridge Loads - Hodgdon Reloading Data Center - data.hodgdon.com
There are a number of other places on the web with load data as well.

If you intend to shoot much cast, I recommend the Lyman Cast Bullet Handbook 4th edition.

Whenever possible I prefer to have more than one source of data for any given load.

I have used Hornady Manuals for as long as I can remember and they pretty much gone by the powder and bullet recommendations they load.