Samenvatting
A collection of essays dealing with occupational health is given. Fretea subjects are psychological tests in the diagnosis of carbon disulphide poisoning, epidemiology of heart disease, interactions of inorganic lead with human red blood cells, the ability for orientation and operations with spatial relationships, the validity of psychological tests on different occupational levels and the impurities of outdoor air. A list of publications 1951-1965 is added.