References
- May 1965 . Threshold Limit Values for 1965, Adopted at the 27th Annual Meeting of the American Conference of Governmental Industrial Hygienists , May , Broadway, Cincinnati : Ohio . 1014
- Martin , L. C. 1955 . “ The Light Microscope. ” . In Physical Techniques in Biological Research , Edited by: Oster , G. and Pollister , A. Vol. 6 , 373 New York : Academic Press .
- Halley , P. D. 1946 . Are Dust Counts Made by Different Laboratories Comparable ? . Amer. Ind. Hyg. Assoc. Quart. , 7 : 15