Here are a few sales / technical items about the Jawa 50 scooters. Above are all model 05 items, which was the earlier designation for the model 20 shown below.
Click on an image to see a larger version.

A road test on a Mustang from British magazine, Motorcycle Mechanics from December 1981.

The press release announcing the introduction of the Mustang.

A service sheet for the 05 scooter published with Motor Cycle And Cycle Trader in September 1964.