Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hieu cac » hieu luc, hieu va, vien cac
vai cua » dai cua, hai cua, lai cua
va dinh » van dinh, va kinh, va tinh
va danh » va dan, va hanh, dia danh
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
y nang » ky nang, ly nang, v nang

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