McGraw-Hill’s Primary Source Investigator (PSI), now available online at www.mhhe.com/psi, is designed to support and enrich the text discussion. PSI gives instructors and students access to more than 650 primary and secondary sources including documents, images, maps, and videos. Students can use these resources to formulate and defend their arguments as well as further their understanding of the topics discussed in each chapter. All assets are also indexed alphabetically as well as by type, subject, place, and time period, allowing students and instructors to locate resources quickly and easily.