Perhaps you should try some spelling variations:
can thiet » dan thiet, cac thiet, cad thiet
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
va hanh » va thanh, va danh, ban hanh
ma hoi » xa hoi, ma hoa, me hoi
vi can » voi can, vi van, i can

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

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