Perhaps you should try some spelling variations:
cac truc » cau truc, cac tru, cac trung
tu sach » thu sach, su sach, te sach
hanh ca » hanh cac, hanh cat, hanh cua
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, may nang
me hoi » le hoi
v nang » va nang, vu nang, van nang
ca cua » co 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 ((y nang) OR (v nang)) ((me hoi) or (ma hoa)). hieu va cac truc va hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (v nang)) ((me hoi) OR (ma hoa)). hieu va cac truc va hanh ca cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) OR (v nang)) ((me hoi) or (ma hoa)). hieu va cac truc va hanh ca cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) OR (v nang)) ((me hoi) or (ma hoa)). hieu va cac truc va hanh ca cua tre*.