Форум Breguet's Aircraft Challenge
The Swiss Hafeli DH-3 from 1917 with a carefully painted out Swiss emblem on the fin and on the fuselage '598'.
One of the machines he built was an original DH-3 from 1917 vintage with the original Argus inline engine. The second machine was a later vintage DH-3 with a Hispano-Suiza engine and Handley Page slats.
The Hafeli DH-3 had an exceedingly long life (as everything has in Suisse ) coming out in 1917 the last examples were still active in the 1930's. About one hundred examples of the DH-3 were built.
So there no Swiss Patents for the designer of the machine August Hafeli.