The study, by James A. Mercy and Mark L. Rosenberg, tracked data between 1973 and 1991. They point out that "A surprisingly large proportion of adolescents report that they routinely carry guns and bring them to school"--14 percent of boys, according to one study, and 7.9 percent of students overall. A 1997 study by the Centers for Disease Control found that one in five students had carried a gun to school in recent months. Mercy and Rosenberg's findings are written up in "Preventing Firearm Violence in and Around Schools," published in Violence in American Schools, edited by Delbert S. Elliott, Beatrix A. Hamburg, and Kirk R. Williams, published by Cambridge University Press, 1998.