Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cau luc » cau truc, cau phuc
hieu va » hieu qua
hieu ve » hieu van
nang ma » tang ma, sang ma, nang cao
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
luc va » duc va, tuc va, loc va
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: tu sach y nang ma hoi. ((((hieu ve) OR (hieu va))) or (lieu va)) cau luc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ma hoi. ((((hieu ve) OR (hieu va))) OR (lieu va)) cau luc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ma hoi. ((((hieu ve) OR (hieu va))) or (lieu va)) cau luc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ma hoi. ((((hieu ve) OR (hieu va))) or (lieu va)) cau luc va hanh vi cua tre*.