There are a lot of oils covered in this book but many of them are rare and unusual. Some common oils are missing as well so this is by no means a definitive guide. The information about each oil is quite generalised; you are better off looking on the internet if you want information. I was quite disappointed with this, however, it is useful if you want to look oils up by category, e.g 'easy breathers' are the oils that help with the respiratory system. I don't think I will use this one that often.