Perhaps you should try some spelling variations:
thien van » thi van
cua triet » cua viet, su triet, va triet
nam nuoc » nam buoc, nam nuoi, nam quoc
nam duoc » nam thuoc, da duoc, dat duoc
te sach » toc sach
ty lang » tay lang, ty hang, tu lang
va hang » van hang, va nang, va lang
va cua » va chua, via cua, ca cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((ty lang) or (ty xang)) xa hoi. thien van ((nam nuoc) OR (nam duoc)) va hang va cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ty lang) OR (ty xang)) xa hoi. thien van ((nam nuoc) OR (nam duoc)) va hang va cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((ty lang) or (ty xang)) xa hoi. thien van ((nam nuoc) OR (nam duoc)) va hang va cua triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((ty lang) or (ty xang)) xa hoi. thien van ((nam nuoc) OR (nam duoc)) va hang va cua triet*.