Pesach Sheni; Path of the Just, The Means of Acquiring Chassidus (Saintliness); Raize Guttman, 5-6-12
Mesillat Yesharim, Rabbi Moshe Chayim Luzzatto, The Path of the Just, Chapter 21, The Means of Acquiring Saintliness, pages 277-282, Feldheim Publishers