Lawrence, P. (1992). Qualifications: Survey and mapping qualifications for the 1990s. London : British Cartographic Society.
Dyfyniad Arddull ChicagoLawrence, Peter. Qualifications: Survey and Mapping Qualifications for the 1990s. London : British Cartographic Society, 1992.
Dyfyniad MLALawrence, Peter. Qualifications: Survey and Mapping Qualifications for the 1990s. London : British Cartographic Society, 1992.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.