The phrase "extensive quotations" refers to using a large portion or many sentences from someone else's work in your own writing or speech. Full definition
There is occasional reference to empirical work, but there are extensive quotations from philosophers, musicians / composers, and musicologists. (newscientist.com)
This is not even to mention actual extant manuscripts of the New Testament — in whole or in part — that date to the first few Christian centuries, and extensive quotations in the writings of the Church Fathers, which run all the way back to the days when the generation contemporary to the alleged events of the New Testament were still alive. (religion.blogs.cnn.com)