. . . "Spectrographic analyses of insoluble-residue samples, Harrison 1° x2° quadrangle, Missouri and Arkansas drill holes nos. 31, 32 and 34"@en . "Spectrographic analyses of insoluble-residue samples, Harrison 1° x2° quadrangle, Missouri and Arkansas : drill holes nos. 31, 32 and 34"@en . . . . . . . . . . . . .