This book is an excellent reference source for oil field personnel. What it has going for it is the sheer volume of information and formulas in it, the simplicity of that information in how it is laid out, organized and given to you and the convenience of it. I think what is inside the book is top notch, but the quality of the book itself suffers some because it seems a little cheap and like it will fall apart easily out in the field unless you are extremely careful with it and it only goes from your clean dainty hands to your bag or briefcase. Even just laminating the cover would have added protection and sturdiness to it. I also would have preferred a section where I could add some of my own notes.