http://kyujanggak.snu.ac.kr/dohae/sub/schDetail.jsp?no=D0226&category=A&sWord=단유도설
http://yoksa.aks.ac.kr/jsp/aa/VolView.jsp?aa10no=kh2_je_a_vsu_22157_001&aa15no=001&aa20no=22157_001_0002
