On a similar note, you generally shouldn't use ampersands (&) in the body of text. I know your book isn't claiming to be literature, but when I'm quickly evaluating whether to buy a little-known book, the use of ampersands is a red flag of an amateur, un-edited, production. Other common ones are using "loose" to mean "lose" and "lead" to mean "led."

Hope this is helpful. I have written a book myself, so I know how much effort it takes.