demograph and American mathematician ( Lemberg, Ostrich 1880 - New York , 1949 )
Foundator of the mathematics demography, he has defined the notion of stable and stationary population; a big part of his work is present in his theory analytic of biologics associations ( 1934 - 1939 )

Others books :     The money value of the man ( written with Louis Dublin, 1930 )
                                Lenght of life ( 1936 )
                                Twenty five years of the Health Progress ( 1937 )