『검경』에서 강(굳셈)과 유(부드러움)라는 개념
https://www.worldmartialarts.wiki/featured/%e3%80%8e%ea%b2%80%ea%b2%bd%e5%8a%8d%e7%b6%93%e3%80%8f%ec%97%90%ec%84%9c-%ea%b0%95%e5%89%9b%ea%b3%bc-%ec%9c%a0%e6%9f%94%eb%9d%bc%eb%8a%94-%ea%b0%9c%eb%85%90/
https://www.worldmartialarts.wiki/featured/%e3%80%8e%ea%b2%80%ea%b2%bd%e5%8a%8d%e7%b6%93%e3%80%8f%ec%97%90%ec%84%9c-%ea%b0%95%e5%89%9b%ea%b3%bc-%ec%9c%a0%e6%9f%94%eb%9d%bc%eb%8a%94-%ea%b0%9c%eb%85%90/