Perhaps you should try some spelling variations:
than phan » thanh phan, toan phan, thanh pham
hieu van » hieu va, thien van, lieu va
tan phan » toan phan, van phan, tai phan
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
van cao » van dao, van bao, van hao
cao duc » dao duc, cao suc, giao duc
tai cua » thai cua, tai cuc, tri cua
cua tu » cua tuc, cua su, cua cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang xa) or (lang xa)) hoi. hieu van cao duc ((tan phan) OR (than phan)) tai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (lang xa)) hoi. hieu van cao duc ((tan phan) OR (than phan)) tai cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (lang xa)) hoi. hieu van cao duc ((tan phan) OR (than phan)) tai cua tu".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (lang xa)) hoi. hieu van cao duc ((tan phan) OR (than phan)) tai cua tu*.