1. The director of revenue may prescribe the form and contents of any return or other document required to be filed under the provisions of sections 143.011 to 143.996.

2. The director of revenue for the purpose of ascertaining the correctness of any return, or for the purpose of making an estimate of taxable income of any person, shall have power to examine or to cause to have examined, by any agent or representative designated by him for that purpose, any books, papers, records, or memoranda bearing upon the matters required to be included in the return, and may require the attendance of the person rendering the return or any officer or employee of such person, or the attendance of any other person having knowledge in the premises, and may take testimony and require proof material for his information, with power to administer oaths to such person or persons.

3. Reports and returns required to be filed under sections 143.011 to 143.996 shall be preserved for four years and thereafter until the director of revenue orders them to be destroyed.