Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
cau tren » dau tren, ca tren, cau treo
sach thu » sach thue, sach thieu, sach tham
dan vai » dan va, dan tai, dan vat
thuc va » thuc vat, thuc dan, thuc day
cu tren » tu tren, dua tren
hieu va » lieu va, hieu qua
long ha » dong ha, cong ha, dong hoa
va dan » ca dan, va dao, va dau
va nam » van nam, ha nam, va nay

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 thu ((dang xay) or (long ha)) hoi. hieu va nam thuc va dan vai ((cau tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thu ((dang xay) OR (long ha)) hoi. hieu va nam thuc va dan vai ((cau tren) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: toc sach thu ((dang xay) or (long ha)) hoi. hieu va nam thuc va dan vai ((cau tren) or (cu tren))*.