Perhaps you should try some spelling variations:
sach tham » sach nha
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
vai cua » dai cua, hai cua, lai cua
va hanh » va thanh, va danh, ban hanh
cau luc » cau truc, cau phuc
qua cau » quan cau, qua cac, qua ca
lang xa » lang ha, dang xay, lang van
nang ma » tang ma, sang ma, nang cao
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: toc sach tham ((lang xa) or (nang ma)) hoi. hieu qua cau luc ((va hanh) OR (van hanh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tham ((lang xa) OR (nang ma)) hoi. hieu qua cau luc ((va hanh) OR (van hanh)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tham ((lang xa) or (nang ma)) hoi. hieu qua cau luc ((va hanh) OR (van hanh)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach tham ((lang xa) or (nang ma)) hoi. hieu qua cau luc ((va hanh) OR (van hanh)) vai cua tre*.