Lazarsfeld also made significant contributions by training many younger sociologists. One of Lazarsfeld's biographers, Paul Neurath, writes that there are "dozens of books and hundreds of articles by his students and the students of his students, all of which still breathe the spirit of this man's work". One of Lazarsfeld's successful students was Barney Glaserpropounder of grounded theory (GT)the world's most quoted method for analyzing qualitative data. Index formations and qualitative mathematics were subjects taught by Lazarsfeld and are important components of the GT method according to Glaser. James Samuel Coleman, an important contributor to social theories of education and a future president of the American Sociological Association, was also a student of Lazarsfeld's at Columbia.