Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau tren » dau tren, ca tren, cau treo
lang van » dang van, tang van, hoang van
dan vat » dang vat, van vat, dan va
thuc va » thuc vat, thuc dan, thuc day
cu tren » tu tren, dua tren
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
lang ha » long ha
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 ty ((lang van) or (lang ha)) hoi. hieu va nam thuc va dan vat ((cau tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((lang van) OR (lang ha)) hoi. hieu va nam thuc va dan vat ((cau tren) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((lang van) or (lang ha)) hoi. hieu va nam thuc va dan vat ((cau tren) or (cu tren))*.