Perhaps you should try some spelling variations:
day hanh » day nhanh, day thanh, dao hanh
thuc day » thuc dan, thuc vat
cam thuc » am thuc, nam thuc, cam thu
su sach » vu sach
hieu va » lieu va, hieu qua
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
so sach » so sanh, bo sach, co sach
y nang » ky nang, ly nang, v nang
di cua » dai cua, doi cua, de cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (so sach)) y nang xa hoi. ((hieu ve) OR (hieu va)) cam thuc day hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) y nang xa hoi. ((hieu ve) OR (hieu va)) cam thuc day hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) y nang xa hoi. ((hieu ve) OR (hieu va)) cam thuc day hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) y nang xa hoi. ((hieu ve) OR (hieu va)) cam thuc day hanh di cua tre*.