Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
ve triet » va trien
su triet » su viet, su tien
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
hanh ki » hanh vi, hanh ky, hanh kien
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
mau hoi » cau hoi, mau ho, mau hop
tu dang » thu dang, tu dong, su dang
va nham » va cham, va tham, va nha

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 tu dang ((mau hoi) OR (mai hoi)). hieu va nham thuc van hanh ki ((su triet) or (ve triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu dang ((mau hoi) OR (mai hoi)). hieu va nham thuc van hanh ki ((su triet) OR (ve triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu dang ((mau hoi) OR (mai hoi)). hieu va nham thuc van hanh ki ((su triet) or (ve triet))".
• Adding a wildcard symbol may retrieve word variants: tu sach tu dang ((mau hoi) OR (mai hoi)). hieu va nham thuc van hanh ki ((su triet) or (ve triet))*.