In any case, Bosnia would probably be in more than one USDA climate zone, depending on the distance from the sea and the elevation. The USDA climate zones are based on the lowest expected winter temperatures. With temperatures in Fahrenheidt, here is the basis for the scale. Maybe this will help you decide.

USDA 2 = -50 to -40 degrees
USDA 3 = -40 to -30
USDA 4 = -30 to -20
USDA 5 = -20 to -10
USDA 6 = -10 to 0
USDA 7 = 0 to +10
USDA 8 = +10 to 20
USDA 9 = +20 to 30

Each zone is also separated into two areas, designated as 7a and 7b, for example. Zone 7a would have temperatures from 0 to +5 degrees F, and zone 7b would have temperatures from +5 to +10 degrees.

http://www.b-and-t-world-seeds.com/European.htm

But this map is not much help for Sweden with its 8 climate zones. And I believe I have 3 different zones in my own garden...