Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
cua viet » ca viet, hoa viet, cua vat
nang xa » lang xa, nang ma, mang xa
qua cac » cua cac
cac tuc » cac toc, cac tu, cac tac
va dan » ca dan, va dau, va dap
va dao » ca dao
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach y ((nang xa) or (nang x)) hoi. hieu qua cac tuc ((va dan) OR (va dao)) va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach y ((nang xa) OR (nang x)) hoi. hieu qua cac tuc ((va dan) OR (va dao)) va cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach y ((nang xa) or (nang x)) hoi. hieu qua cac tuc ((va dan) OR (va dao)) va cua viet*".