Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dung sai » dung tai, dung va, dung dat
van dung » van dong, xay dung, tin dung
cua viet » ca viet, hoa viet, cua vat
song xa » song cua
sach ty » sach y, sach tu, sach thu
va phap » va phat, ban phap
duc van » duc va, duc tan, duc manh
sang xa » lang xa, sang ma, mang xa
sai cua » dai cua, hai cua, lai cua
va pham » van pham, va phat, va phan

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

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