Perhaps you should try some spelling variations:
nang cai » nang tai, nang cap, nang can
va thanh » gia thanh, ban thanh, va tinh
so sach » so sanh, bo sach, co sach
va hanh » van hanh, va danh, ban hanh
cau luc » cau truc, cau phuc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va cau » van cau, va cac, va dau
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((nang cai) or (nang cao)) hoi. hieu va cau luc ((va hanh) OR (va thanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang cai) OR (nang cao)) hoi. hieu va cau luc ((va hanh) OR (va thanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang cai) or (nang cao)) hoi. hieu va cau luc ((va hanh) OR (va thanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang cai) or (nang cao)) hoi. hieu va cau luc ((va hanh) OR (va thanh)) vi cua tre*.