Determination of airborne fibre number concentrations :   a recommended method, by phase-contrast optical microscopy (‎membrane filter method)‎ 

 - Geneva :  WHO,  1997. 
 - 53 pages. 
<br/><br/><label>ISBN: </label>9241544961 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Air Pollutants, Occupational--analysis<br/>Environmental Monitoring<br/>Microscopy, Phase-Contrast--methods