Perhaps you should try some spelling variations:
van thiet » va thiet, dan thiet, van thien
can thiet » dan thiet, cac thiet, cad thiet
van hanh » van thanh, ban hanh, van anh
su sach » so sach
vu sach » vu bach, vu khach
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu ve » hieu va, hieu van
xuc van » duc van, luc van, vuc van
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (vu sach)) ky tang xa hoi. hieu ve cam xuc van hanh vi ((van thiet) or (can thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ky tang xa hoi. hieu ve cam xuc van hanh vi ((van thiet) OR (can thiet)).
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ky tang xa hoi. hieu ve cam xuc van hanh vi ((van thiet) or (can thiet))*.