In practice, if you're only quoting a few lines from a full - length book, you are most likely within fair use guidelines, and do not need to seek permission. (janefriedman.com)
Although producers have specific rights, which can not be denied, fair use guidelines allow educators and students to have access to certain material for limited educational purposes. (hcps.org)
If you think you've gone beyond fair use guidelines, then you should either hold up publishing or remove the material. (janefriedman.com)