(1969). Virginia weed-control guide 1969. Virginia Polytechnic Institute.
Cita Chicago (17th ed.)Virginia Weed-control Guide 1969. Blacksburg: Virginia Polytechnic Institute, 1969.
Cita MLA (9th ed.)Virginia Weed-control Guide 1969. Virginia Polytechnic Institute, 1969.
Atenció: Aquestes cites poden no estar 100% correctes.