a document class provided by AMS, roughly equivalent to book, but conforming to AMS monograph style.
amsbook uses the same input tagging scheme as book, and is intended for preparation of monographs and other documents with chapters. In addition, it incorporates the amsthm conventions, amsmath and amsfonts (extra symbols and Euler alphabets).
A monograph prepared with unmodified \documentclass{book} can have the class replaced by amsbook with minimal file changes to produce a book in the AMS style.
