Cognomen Siefker (Siefker 
) , in all the world, is quite a rare surname. The last name Siefker is characteristic of the United States, where it is a rare surname, Germany, and Canada, where it is a very rare surname.
| VARIANT | COUNTRY |
|---|---|
| Siefker | Germany, Canada, New Zealand, United States |
| phyllis k. siefker (b. 1941) |
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| birgitta maria siefker-eberle German diplomat, DE (b. 1954) |
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| andrew joseph siefker Ph.D. Arizona State University 1997 |
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