"Gokuchû nôto" no nakano "jissen no tetsugaku" no ichi: doitsugo ban "Gokuchû nôto" dai 6 kan eno Hauku jobun no shôkai o chûshin ni [The place of "philosophy of Praxis" in the "Quaderni": A Presentation of the Introduction by W.F. Haug in the sixth volume of the "Gefängnishäfte"]