Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van cam » van nam, van lam, van cau
truc va » thuc va, thuc vat, trung va
tai cua » thai cua, tri cua, dai cua
tuc va » thuc va, tuc xa, duc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang xa hoi. hieu van cam ((tuc va) OR (truc va)) hang ((tai cua) or (tai cuc)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu van cam ((tuc va) OR (truc va)) hang ((tai cua) OR (tai cuc)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. hieu van cam ((tuc va) OR (truc va)) hang ((tai cua) or (tai cuc)) te".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu van cam ((tuc va) OR (truc va)) hang ((tai cua) or (tai cuc)) te*.