Gaya APA
LIBBY, J, R., PERKINS, N, D. (1976).
Modern prestressed concrete highway bridge superstructures : .
San Diego:
Grantville.
Gaya MLA
LIBBY, James, R.., PERKINS, Norman, D..
"Modern prestressed concrete highway bridge superstructures :".
San Diego:
Grantville,
1976.
Buku.