. . . "Standard and tentative methods of sampling and testing highway materials recommended by the Second Conference of State Highway Testing Engineers and Chemists, Washington, D.C., Feb. 23-27, 1920"@en . . "Standard and tentative methods of sampling and testing highway materials : recommended by the Second Conference of State Highway Testing Engineers and Chemists, Washington, D.C., Feb. 23-27, 1920"@en . . . . . . . . "Second Conference of State Highway Testing Engineers and Chemists (1920 : Washington, D.C.)" . . .