Silent Sphinx © 1932 Caille Bros.
Machine's picture.
Collector's Treasury of Antique Slot Machines from Contemporary Advertising - Peter Bach - Page 62, 71 & 86
For Amusement Only - Thomas Gustwiller - Taylor Printing - 1995 - Page 32
The Coin Machine Journal - January 1940 issue
Loose Change Blue Book for Slot Machines [4th Edition]