How Many Isaiah's According To The Dead Sea Scrolls?

"The Isaiah scrolls were the first Biblical texts found, and the first to receive serious study. There is no hint in either of these scrolls of a deutero or trito-Isaiah, to use the language of modern scholarship. The advocate of two or three Isaiah's may suggest that the book was put in its present form prior to the writing of the Qumran manuscripts, but the fact remains that our oldest pre-Christian manuscripts bear witness to the text substantially as we have it in our printed Hebrew Bibles." - Charles Pfeiffer

Link: https://bible-history.com/quotes/charles_f_pfeiffer_2.html