Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
va danh » va dinh, va dan, va hanh
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
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 lang xa hoi. hieu vien ((dai lo) or (dai o)) ((va danh) or (van hanh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang xa hoi. hieu vien ((dai lo) OR (dai o)) ((va danh) OR (van hanh)) vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang xa hoi. hieu vien ((dai lo) or (dai o)) ((va danh) or (van hanh)) vai cua tre*.