Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van than » van thanh, van thang, van tuan
than duc » tran duc, phan duc, than doc
su sach » so sach, vu sach
sach vu » sach va, sach tu, sach uu
vu nang » vuc nang, va nang, vu dang
cao hoi » cau hoi, co hoi, tao hoi
cao hoc » co hoc, cho hoc, chat hoc
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
di cua » dai cua, doi cua, de cua
cua te » cua tu

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 vu nang ((cao hoi) OR (cao hoc)). hieu van than duc va hanh di cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach vu nang ((cao hoi) OR (cao hoc)). hieu van than duc va hanh di cua te".
• Adding a wildcard symbol may retrieve word variants: su sach vu nang ((cao hoi) OR (cao hoc)). hieu van than duc va hanh di cua te*.