Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau tren » dau tren, ca tren, cau treo
nam thuc » nam thuoc, am thuc, nam thu
vat dan » va dan, van dan, vat ran
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
lang ha » long ha
lang xa » dang xay, lang van
cu tren » tu tren, dua tren
va nam » van nam, ha nam, va nay
dan va » doan va, dan ca, ban va

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