Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
phan duc » pham duc, phan tu, phan dau
van phan » van phong, van thanh, luan phan
hieu van » hieu va, thien van, lieu va
sach thu » sach thue, sach thieu, sach tham
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, xach tay
va hanh » van hanh, va thanh, va danh
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 ty) OR (sach thu)) nang xa hoi. hieu van phan duc va hanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang xa hoi. hieu van phan duc va hanh vi ((cua tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach thu)) nang xa hoi. hieu van phan duc va hanh vi ((cua tre) or (cau tren))".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach thu)) nang xa hoi. hieu van phan duc va hanh vi ((cua tre) or (cau tren))*.