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
vu nang » vuc nang, vu dang, v nang
va nang » van nang, da nang, cam nang
cao hoi » cau hoi, co hoi, cao hoc
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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