Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
day thuc » dan thuc, cay thuc, dai thuc
vien day » vien dai, vien da, vien xay
su sach » so sach
ty hang » ly hang, ty xang, thi hang
ty nang » ky nang, ty xang, ly nang
vu sach » vu bach, vu khach
vi cua » vai cua, di cua
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: ((su sach) OR (vu sach)) ((ty nang) or (ty hang)) xa hoi. hieu vien day thuc van hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ((ty nang) OR (ty hang)) xa hoi. hieu vien day thuc van hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (vu sach)) ((ty nang) or (ty hang)) xa hoi. hieu vien day thuc van hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (vu sach)) ((ty nang) or (ty hang)) xa hoi. hieu vien day thuc van hanh vi cua te*.