I understand the bible for Mexico's Sunburst registry seals/labels is Nicholas Follansbee's "The "Sunburst" Registry Seals of Mexico". This was published way back in 1993. Does anybody know if there an updated resource or publication for the seals/labels?
Prexie3c: suggest you visit the web site for the Mexico Elmhurst Philatelic Society International (www.mepsi.org). I think they have a contact field. I'm a member, but haven't visited the site for a while as I'm not working on my Mexico collections right now.