A popular variant is often used to gamble for coffee.
One of the most popular variants is Isabel or Isabella.
Also, in one popular variant, 13 cards are dealt to each player instead of 17.
This became the most popular variant of the MiG-17.
Carl is a popular variant of the name Charles (see there).
A currently popular but expensive variant of this technique is the continuous tracking study.
One popular variant, mentioned in the rule book, removes the investor card.
Étouffée is a popular variant done with crawfish or shrimp.
Raspberry ripple has been a popular variant ever since.
In 1950, Nelson formulated a popular variant of the four color problem.