Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
va trien » va truyen, va thiet, va tuyen
va thanh » gia thanh, ban thanh, va tinh
cap nuoc » dat nuoc
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
hieu ve » hieu va
lang x » lang xa, lang xu, lang _
vai va » mai va, dai va, hai 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 ty ((lang x) OR (nang x)) hoi. ((hieu ve) or (hieu van)) cap nuoc va thanh vai va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((lang x) OR (nang x)) hoi. ((hieu ve) OR (hieu van)) cap nuoc va thanh vai va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((lang x) OR (nang x)) hoi. ((hieu ve) or (hieu van)) cap nuoc va thanh vai va trien".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((lang x) OR (nang x)) hoi. ((hieu ve) or (hieu van)) cap nuoc va thanh vai va trien*.