Perhaps you should try some spelling variations:
su triet » su tien, ve triet
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
thuc va » thuc vat, thuc dan, thuc day
su viet » so viet
truc va » thuc vat, trung va
van cau » van dau, van hau, van chat
hang co » hang cho, hang ca, nang co
ty hang » ly hang, ty xang, thi hang
co hoi » co hoc, co loi

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