Perhaps you should try some spelling variations:
sau triet » su triet, cau triet, va triet
thanh nam » hanh nam, thanh tam, thanh pham
hieu van » hieu va, thien van, lieu va
nam sau » nam sao, nam suu, bam sau
duc gia » quoc gia
cau duc » cao duc, cau luc, chu duc
van cau » van dau, van hau, van chat
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
so hoc » co hoc, mo hoc, so hoa
o hoc » co hoc, mo hoc, y hoc

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 hoc) or (so hoc)). hieu van cau duc gia thanh nam sau triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) nang ((o hoc) OR (so hoc)). hieu van cau duc gia thanh nam sau triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) nang ((o hoc) or (so hoc)). hieu van cau duc gia thanh nam sau triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) nang ((o hoc) or (so hoc)). hieu van cau duc gia thanh nam sau triet*.