Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hanh vai » hanh vi, hanh tai, hanh van
sach tai » sach bai, sach tham, sach xa
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
sach dao » lanh dao
lang xa » lang ha, dang xay, lang van
thuc va » thuc vat, thuc dan, thuc day
hanh va » hang va, hanh vi

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

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