It has been tough for me to find books on essential oils that aren't backed by the marketing department of companies like doterra and young living. I appreciate this book because it is an unbiased take on oils, instead discussing the importance of oil purity and the source/method of creating the oils.
It lists oils that are safe (or not) for pregnancy, though the section on "not safe for pregnancy" .... I noticed, was missing eucalyptus oil. That is, however, remedied in the index of oils, as the notes for eucalyptus do say not to use when pregnant.
Which brings me to the next feature I like. There is a basic index of oils, listing the source of each oil, the uses/benefits, cautions, etc.
After that section, you'll find a section on recipes and blends for various conditions (cold, dandruff, acne, etc)... Again, listed alphabetically.
Overall this is a good basic reference book, particularly since it isn't a marketing device for the companies I mentioned above. Other reference books I have considered would actually say to use that company's blend X, but not tell you what was in it (for proprietary reasons). I like that this book give several recipes and options for creating blends for a given health concern.