How can you tell a Russian desert tortoise's gender?

Male Russian tortoises have longer tails and their cloaca (anal opening) is more slit-like. They tend to carry their tails to one side, tucked under their shell. They also have a spur, a hook-like projection at the tip of their tale. All males have spurs, but some females can also have them. A female Russian tortoise has a fat, wedge shaped tail and her cloaca looks like a asterisk (*). It is very hard to tell if a Russian tortoise is male or female if its shell (from behind neck to where it ends above tail) is less than 5 inches long.