Building Influence for the School Librarian: Tenets, Targets, and Tactics - Paperbackby Gary N. Hartzell (Author) Learn how to promote your library and become an influential player in your school and district. As the school librarian, you play a critical role in impacting student achievement. Learn how to develop your influence and make an even bigger difference both inside and outside the library media center. Author Biography Gary Hartzell is professor emeritus of educational administration at the University of Nebraska at Omaha.