Perhaps you should try some spelling variations:
nang thai » nang tai, dang thai, lang thai
hieu van » hieu va, thien van, lieu va
thai cua » than cua, tai cuc, tri cua
va nang » van nang, da nang, cam nang
cau luc » cau truc, cau phuc
van cau » van dau, van hau, van chat
sach ky » sach y, sach ty, sach kem
cao hoi » cau hoi, cao hoc, tao hoi
cua tre » cua te, cuu tre, cua triet
co hoi » co hoc, co loi
luc va » duc va, tuc va, loc va
sac ky » cac ky, sai ky

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 (sac ky)) nang ((cao hoi) or (co hoi)). hieu van cau luc va nang thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang ((cao hoi) OR (co hoi)). hieu van cau luc va nang thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sac ky)) nang ((cao hoi) or (co hoi)). hieu van cau luc va nang thai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sac ky)) nang ((cao hoi) or (co hoi)). hieu van cau luc va nang thai cua tre*.