There's a lot of quoted material on this site. Most of it is intended to be covered by the principle of "fair use" - that is, it's present only to illustrate a poiint being made about a book under discussion.
There are some longer articles not written by me, for which the permission of the copyright holder has been obtained before reproduction here.
In other cases the material is - as far as I am aware - out of copyright. If you know otherwise please let me know.