Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
tu sach » thu sach, su sach, te sach
va danh » va dinh, va dan, dia danh
vai cua » dai cua, hai cua, lai cua
va hanh » van hanh, va thanh, ban hanh
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
dai lo » dai so, dai ly, dai ho
dai o » dai so, dao o, dai 2

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