Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
cua viet » ca viet, hoa viet, cua vat
thuoc va » thuc va, thuoc ma, thuong va
hieu van » thien van, lieu va, hieu ve
thu sach » thuat sach, thuoc sach, thu hoach
lo nang » ho nang, ly nang, loai nang
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
tu sach » su sach, te sach, tu cach
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

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

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