Clawson, Marion, author
John Hopkins, 1972
Buku Teks
edited by Roland S. Young
Reinhold Publishing Corporation, 1960
Buku Teks
Schmid, A. Allan, author
Resources for The Future, 1968
Buku Teks
The Asphalt Institute
Maryland: The Asphalt Institute, 1974
Buku Teks
Sampson, Robert C., author
Harper & Row, 1955
Buku Teks