Mercator, Gerhard,  and Hondius, Hendrik, b. 1573.  "Warwicum, Northamtonia, Huntingdonia, Cantabrigia, Suffolcia, Oxonium, Buckinghamia, Bedfordia, Hartfordia, Essexia, Berceria, Middelsexia, Southa[m]tonia, Surria, Cantiu[m] & Southsexia."  Map.  1628.  Norman B. Leventhal Map & Education Center,  https://collections.leventhalmap.org/search/commonwealth:6w924q63h (accessed February 20, 2020).