Naomi E. Maurer, Vincent van Gogh, Paul Gauguin (1998). “The Pursuit of Spiritual Wisdom: The Thought and Art of Vincent Van Gogh and Paul Gauguin”, p.49, Fairleigh Dickinson Univ Press
Naomi E. Maurer, Vincent van Gogh, Paul Gauguin (1998). “The Pursuit of Spiritual Wisdom: The Thought and Art of Vincent Van Gogh and Paul Gauguin”, p.15, Fairleigh Dickinson Univ Press