There are several out of print reference manuals I've been looking for and they have them. It appears that you get a free trial and then monthly subscription. It looks like you can download the items to your computer, so an ongoing subscription isn't needed. My concern is that it is a massive copyright fraud site that will download some nasty virus/spyware along with the publication.

Scribd is a document hosting site. Anyone can upload documents to it. Most of what they host is legitimate. But a small percentage of people use it to illegally upload/share copyrighted material.

There's nothing inherently bad/dangerous about using Scribd. Just double-check that the material you're wanting to access isn't actually copyrighted.