율곡선생전서27권
https://db.itkc.or.kr/dir/item?itemId=BT#dir/node?grpId=&itemId=BT&gubun=author&depth=5&cate1=H&cate2=%EC%9D%B4%EC%9D%B4(%E6%9D%8E%E7%8F%A5)&dataGubun=%EB%AC%B8%EC%B2%B4&dataId=ITKC_BT_0201B_0230_010
한국고전종합DB
db.itkc.or.kr
율곡선생전서 19권-26권 성학집요 시리즈
https://db.itkc.or.kr/dir/item?itemId=BT#dir/node?grpId=&itemId=BT&gubun=author&depth=4&cate1=H&cate2=%EC%9D%B4%EC%9D%B4(%E6%9D%8E%E7%8F%A5)&dataGubun=%EA%B6%8C%EC%B0%A8&dataId=ITKC_BT_0201B_0150
이덕무 사소절 청장관전서 27권-31권
https://db.itkc.or.kr/dir/item?itemId=BT#/dir/node?dataId=ITKC_BT_0577A_0280_000_0010
최한기 기측체의
https://db.itkc.or.kr/dir/item?itemId=BT#dir/node?grpId=&itemId=BT&gubun=author&depth=3&cate1=J&cate2=%EC%B5%9C%ED%95%9C%EA%B8%B0(%E5%B4%94%E6%BC%A2%E7%B6%BA)&dataGubun=%EC%84%9C%EC%A7%80&dataId=ITKC_BT_1296A