Family name Koornstra (Koornstra 
) , throughout the world, is a rare last name. The last name Koornstra is habitual in Netherlands, where it is quite a rare surname, North Macedonia, where it is a rare surname, and Argentina, where it is a very rare surname.
| VARIANT | COUNTRY |
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| Koornstra | North Macedonia, Canada, Argentina, United States, Netherlands |
| rinze koornstra Dutch photographer, NL (b. 1889) |
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ruud koornstra Dutch entrepreneur, NL (b. 1964) |
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| matthijs koornstra NL (b. 1941) |
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| jan jacob koornstra researcher |
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| rutger h koornstra researcher (ORCID 0000-0002-5446-755X) |
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