Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
thuc van » thuc vat, thuc dan, thuc va
sach vu » sach va, sach tu, sach uu
hanh ki » hanh vi, hanh ky, hanh kien
vuc van » duc van, luc van, chuc van
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, mang may
va cam » va cham, va cac, va cao
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 vu ((nang ma) or (nang cao)) hoi. hieu va cam ((vuc van) OR (thuc van)) hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach vu ((nang ma) OR (nang cao)) hoi. hieu va cam ((vuc van) OR (thuc van)) hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach vu ((nang ma) or (nang cao)) hoi. hieu va cam ((vuc van) OR (thuc van)) hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach vu ((nang ma) or (nang cao)) hoi. hieu va cam ((vuc van) OR (thuc van)) hanh ki su triet*.