Advanced French composition, by Lewis W. Crawford, Jean M. Gérard, Winthrop H. Rice.Lewis William. Crawford1931
Magnetograms, San Juan, Puerto Rico.U.S. Coast and Geodetic Survey. Magnetic Observatory (San Juan, P.R.)1949EN
Magnetic hourly values, San Juan, Puerto Rico.U.S. Coast and Geodetic Survey. Magnetic Observatory (San Juan, P.R.)1949EN