00000nz  a2200000n  4500
001  KSH1998031665
005  20000406185836
008  980429 n azknn|abn          |a a|a    | 
150  ▼a백트래킹[backtracking]▲
450  ▼a퇴각 검색[退却檢索]▲
450  ▼wr▼i영어▼abacktracking▲
550  ▼a백트랙[back track]▲
550  ▼a역행 제어[逆行制御]▲
550  ▼a제어[制御]▲