Zimmermann, E. W. (1933). World resources and industries: A fanctional appraisal of the availability of agricultural and industrial materials (rev. ed.). Harper & Row.
Dyfyniad Arddull ChicagoZimmermann, Erich W. World Resources and Industries: A Fanctional Appraisal of the Availability of Agricultural and Industrial Materials. rev. ed. New York: Harper & Row, 1933.
Dyfyniad MLAZimmermann, Erich W. World Resources and Industries: A Fanctional Appraisal of the Availability of Agricultural and Industrial Materials. rev. ed. Harper & Row, 1933.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.