Misleading Intro 

First sentence: Czechoslovakia (Czech: Československo, Slovak: Česko-Slovensko/before 1990 Československo)
Isn't it strange? From this I understand, that name Česko-Slovensko was oficial name 1990-92 only in  Slovak/ia, but it was oficial name of whole Czechoslovakia. I'd propose following sentence:
Czechoslovakia (Czech, Slovak: Československo, after 1990 Česko-Slovensko)