Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
qua cham » qua hai, qua cac, va cham
cham cuu » cap cuu, chat cua
va doan » va doanh, van doan, va don
nang xa » lang xa, nang ma, mang xa
tu sach » thu sach, su sach, te sach
va dan » ca dan, va dao, va dau
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: tu sach y ((nang xa) or (nang x)) hoi. hieu qua cham cuu ((va doan) OR (va dan)) va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (nang x)) hoi. hieu qua cham cuu ((va doan) OR (va dan)) va cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang xa) or (nang x)) hoi. hieu qua cham cuu ((va doan) OR (va dan)) va cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang xa) or (nang x)) hoi. hieu qua cham cuu ((va doan) OR (va dan)) va cua viet*.