Perhaps you should try some spelling variations:
luoc can » luc canh, hoc can, luoc dai
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu van
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa
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: te sac ky nang ma hoi. ((hieu ve) OR (hieu va)) cac ((duc van) or (luoc can)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky nang ma hoi. ((hieu ve) OR (hieu va)) cac ((duc van) OR (luoc can)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky nang ma hoi. ((hieu ve) OR (hieu va)) cac ((duc van) or (luoc can)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky nang ma hoi. ((hieu ve) OR (hieu va)) cac ((duc van) or (luoc can)) hanh vi cua tre*.