Last name Piirsoo (Piirsoo 
) , globally, is a rare cognomen. The family name Piirsoo is habitual in Estonia, where it is quite a rare surname, Finland, where it is a rare surname, and the United States, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| Piirsoo | United States, Estonia, Finland |
| viktor piirsoo (b. 1917) |
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| andres piirsoo Estonian biologist, EE (b. 1948) |
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| kai piirsoo Estonian hydrobiologist, EE (b. 1949) |
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| marko piirsoo researcher (ORCID 0000-0002-9447-1350) |
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