[MSDN Library June 1998] Bulgarian-Cyrillic (15.2537479808296%)

MSDN Library Visual Studio 6.0 > Books > Developing International Software for Windows 95 and Windows NT > Appendix Q International Keyboard Layouts

[MSDN Library June 1998] Bulgarian-Latin (14.8227134980709%)

MSDN Library Visual Studio 6.0 > Books > Developing International Software for Windows 95 and Windows NT > Appendix Q International Keyboard Layouts