Perhaps you should try some spelling variations:
hanh cua » manh cua, hang cua, hanh sua
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
hanh ca » hanh cac, hanh cat, hanh cad
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
tuc va » thuc va, truc va, tuc xa

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