Perhaps you should try some spelling variations:
van thiet » va thiet, dan thiet, can thiet
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
ve chat » van chat
va chat » van chat, va phat, cao chat
xuc van » duc van, luc van, vuc van

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 ky tang xa hoi. hieu ((ve chat) OR (va chat)) xuc van hanh vi van thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky tang xa hoi. hieu ((ve chat) OR (va chat)) xuc van hanh vi van thiet".
• Adding a wildcard symbol may retrieve word variants: su sach ky tang xa hoi. hieu ((ve chat) OR (va chat)) xuc van hanh vi van thiet*.