https://www.goveda.com/patent/ES-27-H3 1833-03-31 https://www.goveda.com/patent/ES-28-H3 1833-05-12 https://www.goveda.com/patent/ES-32-H3 1833-10-30 https://www.goveda.com/patent/ES-35-H3 1833-12-15 https://www.goveda.com/patent/ES-40-H3 1833-12-15 https://www.goveda.com/patent/ES-83-H1 1833-04-02 https://www.goveda.com/patent/GB-183306525-A 1833-01-01