Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thanh va » thanh van, hanh va, thanh ha
duc gia » quoc gia
cam duc » cam xuc, cao duc, pham duc
cuu tre » cua tre, cau tren, cau treo
hieu va » lieu va, hieu qua
lang ha » long ha
lang xa » dang xay, lang van
va cam » va cham, va cac, va cao

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 y ((lang xa) OR (lang ha)) hoi. hieu va cam duc gia ((hanh vi) or (thanh va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang xa) OR (lang ha)) hoi. hieu va cam duc gia ((hanh vi) OR (thanh va)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((lang xa) OR (lang ha)) hoi. hieu va cam duc gia ((hanh vi) or (thanh va)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang xa) OR (lang ha)) hoi. hieu va cam duc gia ((hanh vi) or (thanh va)) cuu tre*.