Rav Dovid Leibowitz was a talmid of the Chafetz Chaim and the father of Rav Henoch Leibowitz. I have heard in the name of Rav Yitzchak Hutner that out of all the yeshivas in America, only Rav Leibowitz's yeshiva attempted to create a "mussar yeshiva" in the same style as the European mussar Yeshivas, I.e. A yeshiva that put an emphasis on personal growth and not only learning Torah per se.
My question is, do we possess any material written by Rav Leibowitz?