Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
ty nang » ty xang, ty hang, ly nang
thuc va » thuc vat, thuc dan, thuc day
danh di » danh du, xanh di, danh dien
hanh de » hanh ve, hanh kem
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 ((ty nang) OR (ky nang)) xa hoi. hieu quang nam thuc va ((danh di) or (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty nang) OR (ky nang)) xa hoi. hieu quang nam thuc va ((danh di) OR (hanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty nang) OR (ky nang)) xa hoi. hieu quang nam thuc va ((danh di) or (hanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty nang) OR (ky nang)) xa hoi. hieu quang nam thuc va ((danh di) or (hanh de)) cua tre*.