Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cua viet » ca viet, hoa viet, cua vat
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
qua cac » cua cac
cac luc » cau luc, coc luc, cac nuoc
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: thu sach y ((nang xa) OR (nang ma)) hoi. hieu qua cac luc ((va dan) or (va dao)) va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((nang xa) OR (nang ma)) hoi. hieu qua cac luc ((va dan) OR (va dao)) va cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y ((nang xa) OR (nang ma)) hoi. hieu qua cac luc ((va dan) or (va dao)) va cua viet".
• Adding a wildcard symbol may retrieve word variants: thu sach y ((nang xa) OR (nang ma)) hoi. hieu qua cac luc ((va dan) or (va dao)) va cua viet*.