Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
sach dao » lanh dao
hanh di » hanh vi, hanh de, hang di
van cam » van nam, van lam, van cau
sach lo » sach doi, sach hoi, sach moi
tuc va » thuc va, truc va, tuc xa
di cua » dai cua, doi cua, de cua
x hoi » xa hoi, o hoi, x ho

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

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