Objective -This study sought to determine the characteristics of research materials used by history students in preparing their master's theses. Of which information resources formats did such students make use, and in what proportions? What was the age distribution of resources used? What was the dispersal over journal titles and over subject classification, i.e., the degree of interdisciplinarity? To what extent did the master's students make use of nonEnglish-language materials? To what extent did their institution's library hold the resources in question?The investigator was especially interested in finding quantitative support for what he terms two "hypotheses." The first of these is that historical research depends to a high degree on monographs, journal articles being far less important to it than they are to research in, especially, the natural sciences and technology. The second is that the age distribution of resources important to historical research is much flatter and longer than that of resources upon which researchers in the natural sciences and technology rely.Design -Citation analysis, supplemented with comprehensive catalogue searches.