MLA

German Emigration Co's Surveys in Concho & Tom Green Counties : Showing General Character of Land. Galveston Blueprinting Co?, 187AD. https://collections.library.yale.edu/catalog/15811505.

APA, 6th edition

German Emigration Co's surveys in Concho & Tom Green counties : showing general character of land. (187 C.E.). [Maps]. Galveston Blueprinting Co?, https://collections.library.yale.edu/catalog/15811505.