Perhaps you should try some spelling variations:
vien sach » vien bach, dien sach, viet sach
sach nuoc » sach duoc, cac nuoc, bach tuoc
hieu vien » hieu hien, hieu viec, thieu nien
sach kem » hanh kem
danh du » danh dau, danh tu, dinh du
danh di » xanh di, danh dien, danh gia
nang xa » nang x, lang xa, nang ma
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: su ((sach kem) or (sach y)) nang xa hoi. hieu vien sach nuoc va ((danh di) OR (danh du)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach kem) OR (sach y)) nang xa hoi. hieu vien sach nuoc va ((danh di) OR (danh du)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach kem) or (sach y)) nang xa hoi. hieu vien sach nuoc va ((danh di) OR (danh du)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach kem) or (sach y)) nang xa hoi. hieu vien sach nuoc va ((danh di) OR (danh du)) cua tre*.