This study analyzes types of primary sources cited by South Korean civil engineers. The results are as follows: 1) primary sources by preference are academic journal (55.7%), book (15.6%), seminar contents (10.2%). 2) documents published within last 10 years (26.1%) are cited most often. 3) domestic journal is the primary academic journal cited, and the finding is similar in preference of top-ranked primary reference (domestic and foreign combined). 4) In terms of time, domestic sources are preferred for up-to-date publications, and foreign sources for relatively non-recent publications. 5) The indices of influence and extemporaneity for both domestic and foreign sources do not show high numbers simultaneously.