Missouri Handgun Laws

I'm 22 and I own a handgun. I know that laws are changing on an ongoing basis, and I want to be current and legal, I do not need to be arrested for illegal possession or something like that. I found many sites that describe in detail the laws, one of them being the Moga (MO General Assembly) Laws site, which is the official website of MO Govt. However, this site says nothing about transportation in the cabin. I am almost certain that people over 21 (without the approval CCW) can have a concealable firearm in their cabin, but I would really like to see this information in an official document.

If someone could give a link or tell me where to get an official document that would be great.

The reason I ask is because one of my friends has been arrested and harassed for having one is its interior, even if it was legal. I want to have on hand the bill that allows me that right should I be shot.

And yes, I talked to my local HDD, they told me to go online a find. Pas de chance jusqu'a  predsent.

"People over the age of twenty to one year or more may carry a concealable firearm in the passenger vehicle as long as the firearm is lawfully possessed."

I have no idea about MO, but in my state, you need a CCW. If you do not have a CCW, it must be locked in the trunk.