Formulas and Calculations for Drilling Operations 1st Edition

I bought this book as a reference for various formulas. And, I got the Kindle version so that I could always have it with me. I do not recommend that anyone buy this book.I have found several errors in equations. Some of the equations have incorrect units. Some have incorrect signs. Some have more open parentheses than close parentheses.The formatting overall is terrible. Maybe the hardcover version is better. I've submitted a request to the publisher to verify the errors I found and provide a resolution.