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 » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
vat dan » va dan, van dan, vat ran
dan vai » dan va, dan tai, dan vat
cua tre » cua te, cuu tre, cua triet
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 ky nang xa hoi. hieu va nam thuc vat dan vai ((cau tren) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu va nam thuc vat dan vai ((cau tren) OR (cua tre)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu va nam thuc vat dan vai ((cau tren) or (cua tre))*.