Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
nang o » nang co, nang ho, nang ro
lam su » lam so, lam vu
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: su sach ty nang o hoi. hieu van cau duc tan thanh ((lam su) or (lai su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang o hoi. hieu van cau duc tan thanh ((lam su) OR (lai su)) triet.
• Adding a wildcard symbol may retrieve word variants: su sach ty nang o hoi. hieu van cau duc tan thanh ((lam su) or (lai su)) triet*.