Perhaps you should try some spelling variations:
trang va » hang va
tran van » luan van
vanh dai » van dai, vanh tai, lanh dao
va triet » va thiet, va trien, ve triet
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
v nang » va nang, vu nang, van nang
dai va » mai va

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 ((v nang) or (tran quang)) xa hoi. hieu va cac ((trang va) OR (tran van)) vanh dai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v nang) OR (tran quang)) xa hoi. hieu va cac ((trang va) OR (tran van)) vanh dai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((v nang) or (tran quang)) xa hoi. hieu va cac ((trang va) OR (tran van)) vanh dai va triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((v nang) or (tran quang)) xa hoi. hieu va cac ((trang va) OR (tran van)) vanh dai va triet*.