Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
cua triet » su triet, va triet
hieu van » hieu va, thien van, lieu va
cua viet » ca viet, hoa viet, cua vat
van cam » van nam, van lam, van cau
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach ty
hanh di » hanh vi, hanh de, danh di
hang di » hang doi, hang vi, hang dien
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: thuat sach ky nang o hoi. hieu van cam duc va ((hanh di) or (hang di)) ((cua triet) OR (cua viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky nang o hoi. hieu van cam duc va ((hanh di) OR (hang di)) ((cua triet) OR (cua viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky nang o hoi. hieu van cam duc va ((hanh di) or (hang di)) ((cua triet) OR (cua viet))".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky nang o hoi. hieu van cam duc va ((hanh di) or (hang di)) ((cua triet) OR (cua viet))*.