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Licence: 
Creative Commons Licence
Imaging technique: 
Illustration
Description: 

From Sokolowski (1956).

Creator: 
K. Sokolowski
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith