Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau treo » cau theo, cau tren, cau triet
lang ha » long ha
hieu va » lieu va, hieu qua
lang xa » dang xay, lang van
thuc va » thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
vai cau » va cau, van cau, vai cac
va nay » va ngay, va cay

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 nay ((thuc va) OR (thuc vat)) dan vai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang xa) OR (lang ha)) hoi. hieu va nay ((thuc va) OR (thuc vat)) dan vai cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((lang xa) or (lang ha)) hoi. hieu va nay ((thuc va) OR (thuc vat)) dan vai cau treo".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang xa) or (lang ha)) hoi. hieu va nay ((thuc va) OR (thuc vat)) dan vai cau treo*.