Perhaps you should try some spelling variations:
sach thien » sach thieu, sach tien, cach thien
thien nang » thien bang, thien dang, trien nang
hieu van » hieu va, thien van, lieu va
thanh vi » thanh va, thanh ve, nhanh vi
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
thuc va » thuc vat, thuc dan, thuc day
nang xa » nang x, lang xa, nang ma
ca tren » cau tren, cu tren, la tren
van am » van nam, van lam, van dam

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 thien nang xa hoi. hieu van am thuc va ((thanh vi) OR (hanh vi)) ((cua tre) or (ca tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thien nang xa hoi. hieu van am thuc va ((thanh vi) OR (hanh vi)) ((cua tre) OR (ca tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach thien nang xa hoi. hieu van am thuc va ((thanh vi) OR (hanh vi)) ((cua tre) or (ca tren))".
• Adding a wildcard symbol may retrieve word variants: su sach thien nang xa hoi. hieu van am thuc va ((thanh vi) OR (hanh vi)) ((cua tre) or (ca tren))*.