The major disadvantage of many of these books is that the words in them may sometimes be too difficult for the person who does not have a large vocabulary. Such a person would have a hard time learning these words and could quickly become discouraged. We suggest, therefore, that you scan the materials you are interested in before buying. If most of the words are totally unfamiliar to you, you will probably not get very much out of it. If, however, you recognize many of the words but do not quite know them, then the material is probably at the right level for you.