CHANGING SOURCES OF PUBLISHED INFORMATION

We looked at the types of references in papers published during the first month of 1972, 1982, and 1992 in the Astrophysical Journal and Astronomy & Astrophysics; also those published in the former journal during the first half-years of 1952 and 1962. Some of the results are qualitatively predictable, such as the decrease (from 12% to 1%) in references to observatory publications and inhouse technical reports, and the increase (from 1% to 10%) in references to conference papers. But what are surprising are: (1) the low (less than 3%) reference rate to preprints; showing that they are not replacing journal papers (78%) as the primary source for reliable information; (2) the low (1%) reference rate to theses showing that they are not cited more frequently than average research papers; (3) the low (1%) reference rate to review papers, showing that, contrary to popular belief, very few people cite review papers instead of the original research papers; and (4) the slightly decreasing reference rate (from 6% to 4%) to monographs, showing that despite their greatly increased publication rate, they are gradually being quoted less for research use (as contrasted to tutorial use).