Doctoral Dissertations in Chemistry and Physics: A Longitudinal Study

A bibliometric analysis was conducted over the bibliographies of chemistry and physics doctoral dissertations between 1970 and 2020 to ascertain what types of documents are cited, average ages of cited references and overall changes of dissertation references that have occurred with the advent of electronic resources. The study reviewed 50 dissertations for each discipline with 10 dissertations from each decade (n = 100). Results measured 12,065 total references and found that the median age of journals increased in both chemistry and physics, doubling from 2010 to 2020. Only a few dissertation studies have been done on a longitudinal base to evaluate changes in publication trends. Similarities between the two disciplines with increases in the percentages of journal articles and declines in the number of books, other dissertations, and material types are calculated.