Seemingly inspired by the Theses, the nineteenth century socialist Antonio Labriola called Marxism the "philosophy of praxis". This description of Marxism would appear again in Antonio Gramsci's "Prison Notebooks" and the writings of the members of the Frankfurt School. Praxis is also an important theme for Marxist thinkers such as Georg Lukacs, Karl Korsch, Karel Kosik and Henri Lefebvre, and was seen as the central concept of Marx's thought by Yugoslavia's Praxis School, which established a journal of that name in 1964.