Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
hanh de » hanh ve
thuc va » thuc vat, thuc dan, thuc day
qua nam » quan nam, cua nam, quang nam
vu dang » su dang, vu quang, cua dang
vu nang » vuc nang, va nang, v nang
cua tre » cua te, cuu tre, cua triet

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 ((vu nang) or (vu dang)) xa hoi. hieu qua nam thuc va ((hanh de) or (hanh kem)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((vu nang) OR (vu dang)) xa hoi. hieu qua nam thuc va ((hanh de) OR (hanh kem)) cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ((vu nang) or (vu dang)) xa hoi. hieu qua nam thuc va ((hanh de) or (hanh kem)) cua tre*.