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Odling, WilliamOlszewski, Karol StanislawOláh, George AndrewOmura, SatoshiOnsager, LarsOppenheimer, CarlOrfila, Matheo-José-BonaventureOst, HermannOstromyslenskij, Ivan IvanovičOstwald, WilhelmOstwald, WolfgangOthmer, Donald FrederickÒddo, BernardoÒddo, Giuseppe