Perhaps you should try some spelling variations:
chet duoc » che duoc, cho duoc, che quoc
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
cua tre » cua te, cua triet, dua tren
va hanh » va thanh, va danh, ban hanh
ve chet » ve chat, ve che, se chet
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
cuu tre » cau tren, cau treo
sach 2 » sach y
2 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 2 nang cao hoi. hieu ve chet duoc ((va hanh) OR (van hanh)) lam ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach 2 nang cao hoi. hieu ve chet duoc ((va hanh) OR (van hanh)) lam ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach 2 nang cao hoi. hieu ve chet duoc ((va hanh) OR (van hanh)) lam ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach 2 nang cao hoi. hieu ve chet duoc ((va hanh) OR (van hanh)) lam ((cua tre) or (cuu tre))*.