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