APA (7th ed.) Citation

Wittgenstein, L. (1958). Preliminary studies for the "philosophical investigations": The blue and brown books. Harper.

Chicago Style (17th ed.) Citation

Wittgenstein, Ludwig. Preliminary Studies for the "Philosophical Investigations": The Blue and Brown Books. New York: Harper, 1958.

MLA (9th ed.) Citation

Wittgenstein, Ludwig. Preliminary Studies for the "Philosophical Investigations": The Blue and Brown Books. Harper, 1958.