[Letter : W[illia]m Petty, 1657 September 22 to Samuel Hartlib]
MLA
Petty, William, Sir, 1623-1687. [Letter : W[illia]m Petty, 1657 September 22 to Samuel Hartlib]. Folder 16805. 1657 September 22. https://collections.library.yale.edu/catalog/10034172.
APA, 6th edition
Petty, William, Sir, 1623-1687. (["Folder 16805"])(1657 September 22)[[Letter : W[illia]m Petty, 1657 September 22 to Samuel Hartlib]]. https://collections.library.yale.edu/catalog/10034172.