Perhaps you should try some spelling variations:
van thiet » va thiet, dan thiet, can thiet
truc va » thuc va, thuc vat, trung va
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
ky sang » ky nang, ky dang, ky tang
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, me hoi
xuc va » duc va, tuc va, luc va
tu sac » tu sach, tu cac, tu san

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky sang ((ma hoi) OR (ma hoa)). hieu ve cham ((xuc va) or (truc va)) hanh vi van thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky sang ((ma hoi) OR (ma hoa)). hieu ve cham ((xuc va) OR (truc va)) hanh vi van thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky sang ((ma hoi) OR (ma hoa)). hieu ve cham ((xuc va) or (truc va)) hanh vi van thiet".
• Adding a wildcard symbol may retrieve word variants: tu sac ky sang ((ma hoi) OR (ma hoa)). hieu ve cham ((xuc va) or (truc va)) hanh vi van thiet*.