Perhaps you should try some spelling variations:
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
cac bac » cac bai, cac ban, cac cach
va hanh » van hanh, va thanh, va danh
hanh ca » hanh cac, hanh cat, hanh cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
bac va » ban va, bac ha, bao va
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) or (su sach)) y nang ((le hoi) or (ma hoa)). hieu va cac bac va hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y nang ((le hoi) OR (ma hoa)). hieu va cac bac va hanh ca cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y nang ((le hoi) or (ma hoa)). hieu va cac bac va hanh ca cua tre*.