Perhaps you should try some spelling variations:
sanh tri » thanh tri, dinh tri, minh tri
khoan he » khoa he, khoan ke, khoan le
he trong » he thong, he trung, le trong
so sanh » do sanh
tue cac » tu cac, tuc cac, te cac
co sach » bo sach, cuon sach, hoc sach
tri thi » tri tai, thi thi, tri chi
tai thi » tai chi
bach ha » bac ha, bich ha, sach ha
ha he » hoa he, ha le, va he

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sanh tri tue cac khoan he trong ) or ( co sach ((tri thi) OR (tai thi)) bach ha he trong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sanh tri tue cac khoan he trong ) OR ( co sach ((tri thi) OR (tai thi)) bach ha he trong )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( so sanh tri tue cac khoan he trong ) or ( co sach ((tri thi) OR (tai thi)) bach ha he trong ))".
• Adding a wildcard symbol may retrieve word variants: (( so sanh tri tue cac khoan he trong ) or ( co sach ((tri thi) OR (tai thi)) bach ha he trong ))*.