From Emmanuel Goldstein's work:
THE THEORY AND PRACTICE OF OLIGARCHICAL COLLECTIVISM [0]
PDF download: [1]
History must be rewritten to support the party. (and relegate its history ... Oh, that was someone/something else.)
As a web page: [2]
[0] https://en.wikipedia.org/wiki/The_Theory_and_Practice_of_Oli...
[1] https://archive.org/download/the-theory-and-practice-of-olig...
[2] https://genius.com/Emmanuel-goldstein-the-theory-and-practic...