Perhaps you should try some spelling variations:
luoc can » luc canh, hoc can, luoc dai
va trien » va truyen, va thiet, va tuyen
hieu ve » hieu va, hieu van
duc van » duc va, duc tan, duc manh
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
ma hoi » mai hoi, ma hoa, me hoi
ve cac » va cac, vien cac
vi va » vi van, vai va, vu va

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) OR (xa hoi)). hieu ve cac ((duc van) or (luoc can)) hanh vi va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky nang ((ma hoi) OR (xa hoi)). hieu ve cac ((duc van) OR (luoc can)) hanh vi va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky nang ((ma hoi) OR (xa hoi)). hieu ve cac ((duc van) or (luoc can)) hanh vi va trien".
• Adding a wildcard symbol may retrieve word variants: te sac ky nang ((ma hoi) OR (xa hoi)). hieu ve cac ((duc van) or (luoc can)) hanh vi va trien*.