Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
nang ma » sang ma, nang cao, mang may
thuc va » thuc vat, thuc dan, thuc day
dan tai » van tai, dan thi, han tai
dan vat » dang vat, van vat, dan 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 y ((nang ma) or (tang ma)) hoi. hieu va nam thuc va ((dan tai) or (dan vat)) cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((nang ma) OR (tang ma)) hoi. hieu va nam thuc va ((dan tai) OR (dan vat)) cau treo.
• Adding a wildcard symbol may retrieve word variants: toc sach y ((nang ma) or (tang ma)) hoi. hieu va nam thuc va ((dan tai) or (dan vat)) cau treo*.