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