Over the course of past 12 months I have been developing methods for dating crown caps, first just those from Serbia, and later from ex-YU countries (Croatia, Slovenia, Bosnia, Montenegro, and N. Macedonia). The results were published on my web site http://www.ultrahome.in.rs/crowncaps/chronology/ and following articles:

1. Development of logos on crown caps of the three major beer brands in Serbia in the 21st century
2. Crown caps of other beers in 3 major Serbian brands of the 21st century
3. Serbian radler beers
4. Giveaways for 3 major beer brands in Serbia in 21. century
5. How many Achouffe gnomes do you have in your collection?
6. How many Apple thives do you have in your collection?
7. Dating Serbian crown caps using factory signs
8. Disappearance of words and signs from beer crown caps and labels
9. Serbian crown cap producer Galeb Metal Pack (GMP)
10. Serbian crown cap producer FMP
11. Serbian crown cap producers New Don (n), and Impa (iM)
12. Slovenian and Croatian crown cap producers Plutal and PLUTO
13. Ten methods for dating crown caps

Most detailed breweries:
14. Karlovačka pivovara
15. Zagrebačka pivovara
16. Osječka pivovara
 
Mihailo Alić, researcher and collector, Belgrade, June 2022.
http://www.ultrahome.in.rs/crowncaps