Text ( visual ) : unmediated Offerings and enrollments in science and mathematics in public high schools 1958 / by Kenneth E. Brown and Ellsworth S. Obourn. -- In-house reproduction. -- ix, 87 p., [1] laef of plates : ill., map ; 24 cm. -- (Bulletin / Department of the Interior, Bureau of Education ; 1961, no. 5). -- Photocopy ; Originally published: Washington : G.P.O., 1961 ; "OE-29021" -- T.p. -- (BA61690777) ; https://ci.nii.ac.jp/ncid/BA61690777 Author Heading(s): Brown, Kenneth E. ; Obourn, Ellsworth S.