1. American Conference of Governmental Industrial Hygienists (1948): Transaction of the tenth annual meeting. Cincinnati, Ohio: ACGIH, p 31.
2. American Conference of Governmental Industrial Hygienists (1957): Transaction of the nineteenth annual meeting. Cincinnati, Ohio: ACGIH, p 47.
3. American Conference of Governmental Industrial Hygienists (1963): Threshold limit values for substances in the workroom air adopted by ACGIH for 1963. Cincinnati, Ohio: ACGIH.
4. American National Standard Institute (1969): “Acceptable Concentrations of Benzene.” New York: ANSI, Z37. 4.