I use a number of books that I refer to for my writing and a number that I keep on the shelf that only get referred to now and then. All are useful though.
Self-Editing for Fiction Writers. Rennie Browne and Dave King
Romancing the Beat. Gwen Hayes
Writers’ Handbook 2018. Editor J Paul Dyson.
Mastering Amazon Ads. Brian D Meeks
An Authors GFuide To Goodreads. Barb Drozdowich
Help! My Facebook Ads Suck. Michael Cooper
Scrivener for Dummies. Gwen Hernandez
The Oxford English Dictionary. Oxford Press
Grammatically Correct. Anne Stilman
The Associated Press Stylebook. Associated Press
Essential Public Affairs for journalists. James Morrison
Along with countless online documents, How-To guides and Blog comments.