Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
hieu vien » hieu hien, thieu nien, hieu tieng
danh sai » dung sai, danh bat, danh dau
bach lop » cac lop, ba lop, bach hoa
tu sach » thu sach, te sach, tu cach
sai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
su sach » so sach, vu sach
lop va » lap va, hop va, nop va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ky nang xa hoi. ((hieu vien) OR (hieu viec)) bach lop va danh sai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang xa hoi. ((hieu vien) OR (hieu viec)) bach lop va danh sai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang xa hoi. ((hieu vien) OR (hieu viec)) bach lop va danh sai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang xa hoi. ((hieu vien) OR (hieu viec)) bach lop va danh sai cua tre*.