Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
danh hoi » danh hoa, danh hoc, dang khoi
hieu van » hieu va, thien van, lieu va
sach thu » sach thieu, sach tham, cach thuc
cam truc » cau truc, nam truc, lam truoc
dan hoi » dan hoc, dai hoi, van hoi
van cam » van nam, van lam, van cau
truc va » thuc va, thuc vat, trung va
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: thu ((sach thu) or (sach thue)) nang xa hoi. hieu van cam truc va ((danh hoi) OR (dan hoi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach thu) OR (sach thue)) nang xa hoi. hieu van cam truc va ((danh hoi) OR (dan hoi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach thu) or (sach thue)) nang xa hoi. hieu van cam truc va ((danh hoi) OR (dan hoi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach thu) or (sach thue)) nang xa hoi. hieu van cam truc va ((danh hoi) OR (dan hoi)) cua tre*.