| Matthew Schwartz 2016 , , USA: Harvard University, Page 1, Part 1 | Matthew Schwartz 2016 , , USA: Harvard University, Page 3, Part 2 |
|---|---|
| Matthew Schwartz 2016 , , USA: Harvard University, Page 11, Part 6 |
Itten Johannes 1970 , , Usa: David Van Nostrand Co, Page 29-31.