For 10 points, identify this period of liberal reforms in 1968 in Czechoslovakia.
Ludvik Vakulik wrote "The Two Thousand Words" during this event, and Ota Sik was one of  the early leaders of this event, In this event's aftermath, Jan Palach set himself on fire, and it began when Antonin Novotny was resigned and was replaced by Ludvik Svoboda. This event's  leader was eventually replaced by Gustav Husak, and this event saw the application of the  Brezhnev Doctrine, as the Soviets eventually decided to invade and put an end to the reforms put in place by Alexander Dubcek. For 10 points, identify this period of liberal reforms in 1968 in Czechoslovakia.
Ludvik Vakulik wrote "The Two Thousand Words" during this event, and Ota Sik was one of  the early leaders of this event, In this event's aftermath, Jan Palach set himself on fire, and it began when Antonin Novotny was resigned and was replaced by Ludvik Svoboda.
{Prague Spring} or Praska Jaro