Preston, R. N., & Preston, M. L. (2000). Washington gold & gems maps, then and now: Gold/silver, agate, actinolite, adventurine ... thundereggs, tourmaline, zeolite. Northwest Dist.].
Cita Chicago Style (17a ed.)Preston, Ralph N., y M. L. Preston. Washington Gold & Gems Maps, Then and Now: Gold/silver, Agate, Actinolite, Adventurine ... Thundereggs, Tourmaline, Zeolite. [Tidewater, Or.: Northwest Dist.], 2000.
Cita MLA (8a ed.)Preston, Ralph N., y M. L. Preston. Washington Gold & Gems Maps, Then and Now: Gold/silver, Agate, Actinolite, Adventurine ... Thundereggs, Tourmaline, Zeolite. Northwest Dist.], 2000.
Precaución: Estas citas no son 100% exactas.