Before revision: While this can be derived from the full classification, a simpler proof (less than a page) is given in Appendix 12 of Aaronson-Grier-SchaefferAGS Aaronson-Grier-SchaefferS.
After revision: While this can be derived from the full classification, a simpler proof (less than a page) is given in Appendix 12 of Aaronson-Grier-SchaefferS.