Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thuc dan » thuc hanh, hoc dan, thuc vat
thuc van » thuc vat, thuc va, thuc hanh
tang mau » trang mau, dang mau, thanh mau
va tham » van tham, va cham, va thanh
hanh ki » hanh vi, hanh ky, hanh kien
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
ki su » ky su

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