Perhaps you should try some spelling variations:
sach tham » sach nha
sach thu » sach thue, sach thieu, cach thuc
cuu tre » cua tre, cau tren, cau treo
han tai » hang tai, nhan tai, van tai
van han » van hanh, van phan, van nhan
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
su viet » so viet

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 thu) or (sach tham)) nang xa hoi. hieu va cac duc van han tai ((cuu tre) or (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach thu) OR (sach tham)) nang xa hoi. hieu va cac duc van han tai ((cuu tre) OR (su viet)).
• Adding a wildcard symbol may retrieve word variants: toc ((sach thu) or (sach tham)) nang xa hoi. hieu va cac duc van han tai ((cuu tre) or (su viet))*.