Final answer:
The areas of a textbook with supplementary materials and additional information, such as historical documents, a glossary, and further readings, are found in the appendix.
Step-by-step explanation:
The areas of a textbook that include supplementary materials and additional information to the main text can be found in the appendices. These appendices may consist of extra historical information, documents, tangents that are relevant but not central to the text, glossaries, photo credits, and bibliographies. For example, Appendix.1 might list important organizations, while Appendix.5 provides a glossary of key terms used throughout the textbook. An appendix serves as a valuable resource for students to explore topics further or review terms and definitions. Additionally, the Appendix.7 Bibliography offers a compact list of further readings, suggesting a more in-depth study for those interested.