Perhaps you should try some spelling variations:
hanh vai » hanh vi, hanh va, hanh tai
thuc dan » thuc hanh, hoc dan, thuc vat
doc sach » hoc sach, nuoc sach, dac sac
toc sach » hoc sach, thuoc sach, nuoc sach
cua viet » ca viet, hoa viet, cua vat
lang xa » lang ha, dang xay, lang van
ty lang » tay lang, ty xang, ty hang
hieu vi » hieu voi, hieu va, hieu ve
thuc va » thuc vat, thuc day
vai cua » dai cua, hai cua, lai cua

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

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