Baker, G. P., & Hacker, P. M. S. (1988). Wittgenstein: Rules, Grammar and Necessity / G. P. Baker & P. M. S. Hacker. Blackwell.

Baker, Gordon P., and Peter Michael Stephan Hacker. Wittgenstein: Rules, Grammar and Necessity / G. P. Baker & P. M. S. Hacker. Oxford: Blackwell, 1988.

Baker, Gordon P., and Peter Michael Stephan Hacker. Wittgenstein: Rules, Grammar and Necessity / G. P. Baker & P. M. S. Hacker. Blackwell, 1988.