Perhaps you should try some spelling variations:
can thiet » dan thiet, cac thiet, cad thiet
van thanh » ban thanh, van tuan
thu sach » tu sach, thuat sach, thuoc sach
hieu vu » hieu ve, hieu su, dieu vu
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
ma hoi » mai hoi, xa hoi, ma hoa
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. ((hieu vu) OR (hieu va)) cham soc ((va hanh) or (van thanh)) vi can thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ma hoi. ((hieu vu) OR (hieu va)) cham soc ((va hanh) OR (van thanh)) vi can thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ma hoi. ((hieu vu) OR (hieu va)) cham soc ((va hanh) or (van thanh)) vi can thiet".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ma hoi. ((hieu vu) OR (hieu va)) cham soc ((va hanh) or (van thanh)) vi can thiet*.