When blue is blue

Scientific treatise and study on the composition of the paint on the Protectorate 5h blue linden leaf stamp. Study of the dependence of the amount of paint on the color shade of postage stamps.

03. 05. 2025

Log in to the client zone

Please, enter your email and password:

Email: 

Password: 




Request password

(If you have forgotten your login password)



Check email address registration

(If you want to check whether the email address is already registered)




Philatelic partners

POFIS - Postal philatelic service
EXPONET - Virtual international philatelic exhibition
Slovak Society of Olympic and Sports Collectors
Filaso.cz ...or philatelists for themselves
OLYMPSPORT - Czech Association for Olympic and Sport Philately
ZSF - Union of Slovak Philatelists