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