| 1957 KOCK Doubly Resonant Filter Patent Print |
| 1941 KOCK Means Generating Electric Oscillations |
| 1944 KOCK Oscillation Generating System Patent |
| 1954 KOCK Electrical Musical Instrument Patent |
| 1940 KOCK Electrical Contact BALDWIN Patent 11009 |
| 1938 KOCK Electrical Generation Musical Tones |
| 1943 KOCK Electrical Musical Instrument Patent |
| 1939 KOCK Automatic Oscillation Starter Patent |
| 1959 KOCK Utilization Higher Order Acoustic Waves |
| 1954 KOCK Compressional Wave Guide System Patent |
| Marianne Kock Det Basta Med [BEST OF] |
| South Africa P91 10 Shillings sign de Kock 1956 XF++ |
| South Africa P119 5 Rand sign G.de Kock 1973 XF/aUNC |
| South Africa P106 Ten Rand sign de Kock 1961 VF++ |
| South Africa P93 One Pound sign de Kock 1956 XF++ |
| Dutch Indies 1930 regd. cover Fort de Kock to Berlin |
| SET OF 3 ANTIQUE FRENCH BOOKS"OEVRES DE CH. P. DE KOCK" |
| LIMITED FRIQUETTE by CHARLES PAUL DE KOCK HB |
| Netherlands Indies Official Letter of Fort De Kock |
| Dutch Indies 1930 regd. cover Fort de Kock to Berlin |
| Heckler & Kock USP pistol pewter pin |