Perhaps you should try some spelling variations:
qua cham » qua hai, qua cac, va cham
cham luc » cham soc, nhan luc, cham cuu
va danh » va dinh, va dan, va hanh
va vanh » va van, va hanh, va anh
sach ky » sac ky, sach y, sach ty
vu sach » vu bach, su sach, vu khach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((nang xa) or (nang ma)) hoi. hieu qua cham luc ((va vanh) OR (va danh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang xa) OR (nang ma)) hoi. hieu qua cham luc ((va vanh) OR (va danh)) dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang xa) or (nang ma)) hoi. hieu qua cham luc ((va vanh) OR (va danh)) dai cua tre*".