Patente

[1]

H. Kern

Zirkel. Patent Nr. CH 29050/508. Eidgenössisches Amt für geistiges Eigtentum (1904).
[2]

H. Kern

Ruling-Pen. Patent Nr. US 804011. United States Patent Office (1905).
[3]

H. Kern

Joint for Compasses. Patent Nr. US 808205. United States Patent Office (1905).
[4]

H. Kern

Compasses. Patent Nr. US 814453. United States Patent Office (1906).