MLA

Valck, G. (Gerard), 1651-1726. Circulus Saxoniae Inferioris, divisa in ducatus Brunsuici, Zellae, Holsatiae, Meklenburgi et Bremae, archiepiscopatum Magdeburgi, et episcopatus Hildesii et Halberstadii [cartographic material]. ca. 1702?]. https://collections.library.yale.edu/catalog/16618346.

APA, 6th edition

Valck, G. (Gerard), 1651-1726. (ca. 1702?])[Circulus Saxoniae Inferioris, divisa in ducatus Brunsuici, Zellae, Holsatiae, Meklenburgi et Bremae, archiepiscopatum Magdeburgi, et episcopatus Hildesii et Halberstadii [cartographic material]]. https://collections.library.yale.edu/catalog/16618346.