The Pan-Slavic colors reference article from the English Wikipedia on 24-Apr-2004
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Pan-Slavic colors

Helping orphans the way you would do it
The Pan-Slavic colors, red, blue and white, are colors used on the flags of most Slavic states and peoples. Their use symbolises the common origin of the Slavic peoples. They were first used on and originate from the Flag of Russia.
Image:Croatia_flag_medium.png
Flag of Croatia		 Image:Czech_republic_flag_medium.png
Flag of Czech Republic		 Image:Russia_flag_medium.png
Flag of Russia		 Image:Serbia_flag_medium.png
Flag of Serbia
Image:Slovakia_flag_medium.png
Flag of Slovakia		 Image:Slovenia_flag_medium.png
Flag of Slovenia		 Image:Sorbs_flag_medium.png
Flag of Sorbs		 Image:Yugoslavia_flag_medium.png
Flag of Yugoslavia

The flag of Bulgaria also originated from the same Pan-Slavic colors, but the blue was replaced with green, because Bulgaria was developed as agricultural country after its independence in 1878. The flag of Montenegro also consist of the same colours, in order as the flag of Serbia, but its blue color is brighter. The flag of Eastern Rumelia, a former Turkish province now part of Bulgaria, also consisted of the same colors.

These three colors are, without the same symbolism, also used on the flags of many non-Slavic nations, including the United States, the United Kingdom, and France.

See also: Pan-Slavism, Pan-African colors, Pan-American colors