There are many online resources where you can find free Unix Editing books to download in PDF format, including online textbooks, ebooks, lecture notes, and more, covering basic, beginner, and advanced concepts for those looking for an introduction to the subject or a deeper understanding of it.
These slides concentrate on vi because it is very fast and always
available. Although the set of commands is very cryptic, by learning a small
subset of the commands, you can edit text very quickly.