More than 53,000 citations from 609 dissertations published at The Ohio State University between 1998-2012 representing four science disciplines--civil engineering, computer science, mathematics and physics--were examined to determine what, if any, preferences or trends exist. This case study seeks to identify whether or not researcher preferences have changed over time when determining which citation categories are cited in their dissertation. These results revealed that books, articles, and conference papers continue to rank highest in popularity among researchers, however, some shifts have occurred among categories across all four disciplines. When comparing overall rankings, web pages have clearly shown an increase in popularity jumping from 9th place in 1998 to 4th place in 2012. Most surprising, is the decline in usage of theses and dissertations from 6th place (1998) to 8th place (2012) even though improved electronic access has increased availability during the 15-year period.