Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
sach tay » xach tay, sach hay, sach nay
dan vat » dang vat, van vat, dan dat
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
lang ha » long ha
lang xa » dang xay, lang van
dan va » doan va, dan ca, ban va
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 tay ((lang xa) or (lang ha)) hoi. hieu va nam thuc va ((dan vat) OR (dan va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach tay ((lang xa) OR (lang ha)) hoi. hieu va nam thuc va ((dan vat) OR (dan va)) cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach tay ((lang xa) or (lang ha)) hoi. hieu va nam thuc va ((dan vat) OR (dan va)) cuu tre*".