Persons employed by a school district as school librarians, assisted by other certificated personnel where deemed necessary, are responsible to perform the duties assigned by the school district governing board, including, but not limited to, supplementing classroom instruction, helping and instructing pupils in the choice and use of library materials, planning and coordinating school library programs with the instructional programs of a school district, selecting materials for school libraries, and conducting a planned course of instruction for those pupils who assist in the operation of school libraries, subject to such policies, rules and regulations as may be established by the governing board for the operation and utilization of school libraries. Classified personnel assigned school library duties are to be under the supervision of certificated personnel; instructional aides assigned to school libraries are subject to the provisions of Education Code Sections 45340 through 45349; pupils are under the supervision of certificated personnel.