Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hang dien » quang dien, dang dieu, nhan dien
hieu van » hieu va, thien van, lieu va
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
cau duc » cao duc, cau luc, chu duc
hanh de » hanh ve, hanh kem
van cau » van dau, van hau, van chat
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach ky nang ((o hoi) OR (o hoc)). hieu van cau duc va ((hanh de) or (hang dien)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky nang ((o hoi) OR (o hoc)). hieu van cau duc va ((hanh de) OR (hang dien)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky nang ((o hoi) OR (o hoc)). hieu van cau duc va ((hanh de) or (hang dien)) su triet".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky nang ((o hoi) OR (o hoc)). hieu van cau duc va ((hanh de) or (hang dien)) su triet*.