Lyman M Kells, Willis F Kern &, . (1951). Plane and Spherical Trigonometry. New York: MGH.
Lyman M Kells, Willis F Kern &, . 1951. Plane and Spherical Trigonometry. New York: MGH.
Lyman M Kells, Willis F Kern &, . Plane and Spherical Trigonometry. New York: MGH. 1951.