Lakeisha, a first-year staff accountant, was researching a tax issue and found what appears to be the answer to her question in her introductory tax textbook that she bought three years ago. She is thrilled because she thought it would take much longer to find her answer. What type of authority is the textbook? What are other examples of this type of authority? Can Lakeisha base her research conclusion on the textbook or similar authorities? Any suggestions for Lakeisha?