^ abHintikka, Jaakko; Hintikka, Merrill B. (1983). "Some remarks on (Wittgensteinian) logical form". Synthese. 56 (2): 155–170. doi:10.1007/BF00485322.
^Wittgenstein in Cambridge Letters and Documents 1911 - 1951. Wiley. 2012. p. 210.
Further reading
"Some remarks on (Wittgensteinian) logical form" revised and reprinted in Hintikka, Merrill B. and Jaakko Hintikka, (1986). Investigating Wittgenstein. Oxford, UK; New York, NY, USA: Blackwell. ISBN978-0-631-14179-2