Word: kyusaku
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Dates: during 1940-1949
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Original rhythm boys were Gynecologists Kyusaku Ogino of Japan and Hermann Knaus of Prague. They found that every woman has a sterile period of about two weeks in her menstrual cycle, concluded that such periods could be calculated as accurately as astronomers chart eclipses of the moon. To simplify elaborate mathematical computations, some ten companies throughout the U. S. put out a line of graphs, wheels, calendars and slide rules, which sell from...
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