BN Service tchèque : Příručný slovník naučný, 1967, t. 4
Internet, alt.obituaries, 2004-08-26
Information trouvée : décès 2004, Sik, the author of Czechoslovakia's 1960s economic reform, was among the
leaders who tried to liberalize communist rule in what became known as the "Prague
Spring." Like others in the government, he was forced to resign as deputy prime minister
after the 1968 invasion by the Soviet-led Warsaw
Jarní probuzení : iluze a skutečnost / Ota Šik, 1990