Scholars writing books that are widely used to support teaching in higher education may be undervalued because of a lack of evidence of teaching value. Although sales data may give credible evidence for textbooks, these data may poorly reflect educational uses of other types of books. As an alternative, this article proposes a method to search automatically for mentions of books in online academic course syllabi based on Bing searches for syllabi mentioning a given book, filtering out false matches through an extensive set of rules. The method had an accuracy of over 90% based on manual checks of a sample of 2,600 results from the initial Bing searches. Over one third of about 14,000 monographs checked had one or more academic syllabus mention, with more in the arts and humanities (56%) and social sciences (52%). Low but significant correlations between syllabus mentions and citations across most fields, except the social sciences, suggest that books tend to have different levels of impact for teaching and research. In conclusion, the automatic syllabus search method gives a new way to estimate the educational utility of books in a way that sales data and citation counts cannot.