Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
nang xa » nang x, lang xa, nang ma
cac duc » cac du, cac dac, cac nuoc
cao duc » dao duc, cao suc, giao duc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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 (thu sach)) ky nang xa hoi. hieu vien ((cac duc) OR (cao duc)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang xa hoi. hieu vien ((cac duc) OR (cao duc)) va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (thu sach)) ky nang xa hoi. hieu vien ((cac duc) OR (cao duc)) va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang xa hoi. hieu vien ((cac duc) OR (cao duc)) va hanh vi cua tre*.