The purpose of this study is to determine the materials used by graduate students in engineering and to guide library collection development decisions. A literature review shows citation studies are useful in developing core journal lists and determining appropriate allocations between journals and monographs. This case study found that journals (38%), conference papers (19%), and books (18%) are the most heavily used formats, with books aging more slowly than other formats. Core journal lists are developed by total citations and by number of citing authors. Variations among engineering disciplines were identified, including variations in format, age, and subject classification of journals. Areas for further research are noted.