Perhaps you should try some spelling variations:
hieu viec » nhieu viec, sieu viet, hieu hien
toc sach » hoc sach, doc sach, thuoc sach
dinh vai » dinh van, dinh vi, dinh va
dai luan » bai luan, dan luan, dat luan
luan va » luan van, luat va
hieu ve » hieu va, hieu van
va dinh » van dinh, va kinh, va tinh
cua tu » cua tuc, cua cu, cua te
y nang » ky nang, ly nang, v nang
cua su » qua su
x hoi » xa hoi, o hoi, x ho

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 y nang x hoi. ((hieu viec) OR (hieu ve)) dai luan va dinh vai ((cua tu) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang x hoi. ((hieu viec) OR (hieu ve)) dai luan va dinh vai ((cua tu) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang x hoi. ((hieu viec) OR (hieu ve)) dai luan va dinh vai ((cua tu) or (cua su))".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang x hoi. ((hieu viec) OR (hieu ve)) dai luan va dinh vai ((cua tu) or (cua su))*.