Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
va thanh » gia thanh, ban thanh, va tinh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va danh, ban hanh
so viet » hoc viet
hieu va » lieu va, hieu qua
hieu ve » hieu van
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
vi so » vi soi, vi mo, va so

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 sang ma hoa. ((hieu ve) or (hieu va)) nam thuoc ((va hanh) OR (va thanh)) vi so viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang ma hoa. ((hieu ve) OR (hieu va)) nam thuoc ((va hanh) OR (va thanh)) vi so viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky sang ma hoa. ((hieu ve) or (hieu va)) nam thuoc ((va hanh) OR (va thanh)) vi so viet".
• Adding a wildcard symbol may retrieve word variants: su sach ky sang ma hoa. ((hieu ve) or (hieu va)) nam thuoc ((va hanh) OR (va thanh)) vi so viet*.