The ATI study guide is probably the best book available but it is not perfect. Some topics in the science section are only vaguely covered and you will need to rely on your previous academic training for them. It is not a replacement for high school. You may need to use additional books to help you go into details. (e.g. chemistry, organ systems, DNA/RNA, geology) Try not to think too much about what might be missing. Focus on the effort you have already made to study for the test. The hardest part on any test is to control your fears. Everybody has this anxiety and in a way it is a good sign because it shows you care about the results. Once you give your full attention to the questions the anxiety goes away, especially when you find a few answers that you know are correct. Good luck!