Grout 2016. Grout, James (2016). "John Gerard". Encyclopaedia Romana. University of Chicago. Archived from the original on 19 February 2024. Retrieved 3 November 2016.
Grout 2016. Grout, James (2016). "John Gerard". Encyclopaedia Romana. University of Chicago. Archived from the original on 19 February 2024. Retrieved 3 November 2016.