Brands of the world has a collection of logos, but a corporate identity guide is much more than that. It specifies proper usage of the logo and other trademarks, including color, positioning, accompanying fonts if relevant, with illustrations of such, and also illustrations of erroneous uses that should be avoided.

This may include how the corporate identity is applied to signs, vehicle markings, packaging, stationery (including letterhead, envelopes, business cards, etc.), print, broadcast, and other media advertising, and other collateral.

Such a document can range from a small pamphlet to a collection of ponderous bound tomes depending on its scope.

As far as where to find a PDF of one, you'll probably have to ask the companies directly. Someone in the marketing department likely has access to this information to provide to advertising bureaus and the like, but they may regard the information as proprietary.

try googling for a university style guide:

"logo usage" "pantone" "university"

or

"visual identity"

or

"visual identity guidelines"

and a bunch will come up.

Well, what do you know, so it does!
A search for "corporate identity manual" turned up a lot for me including one for FedEx.