What is the proper way to order vendor prefixes?

The rub

• CSS Tricks says that the order of the display vendor prefixes for flexbox is important and shows one ordering (-webkit-box, -moz-box, -ms-flexbox, -webkit-flex, flex)
• MDN shows a different order than CSS Tricks and swaps -moz-box out for -moz-flex (-webkit-box, -webkit-flex, -moz-flex, -ms-flexbox, flex)
• Bourbon shows yet a different order and brings in box, which the other two pages don't even mention (-webkit-box, -moz-box, box, -webkit-flex, -moz-flex, -ms-flexbox, flex)

The questions

• Is order really important?
• What is the correct way to do this?