Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
tu cach » tu cac
nang xa » nang x, lang xa, nang ma
thuc va » thuc vat, thuc dan, thuc day
dan dau » danh dau, doan dau, van dau
dau cua » dai cua, day cua, cau cua
va dan » ca dan, va dao, va dau
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (toc sach)) ky nang xa hoi. hieu van nam thuc va dan dau cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (toc sach)) ky nang xa hoi. hieu van nam thuc va dan dau cua te.
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (toc sach)) ky nang xa hoi. hieu van nam thuc va dan dau cua te*.