MLA

Cromwell, Oliver, 1599-165, Ellyson, Thomas. To His Hignesse, Oliver, lord protector of England, Scotland and Ireland; and to all emperours, kings, princes and governours throughout the whole world. The petition of Thomas Ellyson, late shepheard of Easington .... [1654?]. https://collections.library.yale.edu/catalog/2028570.

APA, 6th edition

Cromwell, Oliver, 1599-165, & Ellyson, Thomas. ([1654?])[To His Hignesse, Oliver, lord protector of England, Scotland and Ireland; and to all emperours, kings, princes and governours throughout the whole world. The petition of Thomas Ellyson, late shepheard of Easington ...]. https://collections.library.yale.edu/catalog/2028570.