Perhaps you should try some spelling variations:
ban khanh » ban hanh, ban thanh, van khanh
hieu van » hieu va, thien van, lieu va
xuc ban » duc ban, cuc ban, quoc ban
cac xuc » cam xuc, cac nuoc, chat xuc
van cac » van hac, van cau, van bac
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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) OR (sach ty)) nang o hoi. hieu van cac xuc ban khanh ((dai cua) or (tri cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) nang o hoi. hieu van cac xuc ban khanh ((dai cua) OR (tri cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) nang o hoi. hieu van cac xuc ban khanh ((dai cua) or (tri cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) nang o hoi. hieu van cac xuc ban khanh ((dai cua) or (tri cua)) tre*.