Perhaps you should try some spelling variations:
thuc ban » thuoc ban, thuc dan, thu ban
can thuc » dan thuc, van thuc, cay thuc
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
ban dan » ban hang, ban hanh, ban quan
van can » van canh, van ban, ban can
nang ma » tang ma, sang ma, nang cao
dan vi » doan vi, don vi, dan va
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((nang x) or (nang ma)) hoi. hieu van can thuc ban dan vi ((cua te) OR (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang x) OR (nang ma)) hoi. hieu van can thuc ban dan vi ((cua te) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang x) or (nang ma)) hoi. hieu van can thuc ban dan vi ((cua te) OR (cua tu))".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang x) or (nang ma)) hoi. hieu van can thuc ban dan vi ((cua te) OR (cua tu))*.