https://books.google.it/books?id=SrigYz35QkoC&pg=PA3&hl=it&source=gbs_selected_pages&cad=1#v=onepage&q&f=false

https://westminsterresearch.westminster.ac.uk/download/2ac2120f0ed889d4ae48e770b0342e8fe22e7636ee62ec1d7604e332ed3ac122/78614/Bradley-%20A%20Global%20Language%20for%20Graphology.pdf]]>