https://books.google.co.uk/books?id=IoxWAgAAQBAJ&pg=PA267&lpg=PA267&dq=lettrism+and+hurufiyya&source=bl&ots=dq1O8Upz_p&sig=yBJCqWfF20LedEl80HVpXJQib-A&hl=en&sa=X&ved=0ahUKEwj9nOeCv4TLAhXFvRQKHW53CXQQ6AEIJDAC#v=onepage&q=lettrism%20and%20hurufiyya&f=false
