Perhaps you should try some spelling variations:
ve triet » va trien, su triet
nam thuc » nam thuoc, am thuc, nam thu
cam thuc » am thuc, cam thu, can thuc
va hanh » van hanh, va thanh, va danh
su sach » so sach, vu sach
va lang » va nang, hoa lang
da lang » dua lang, da nang, da dang
hieu ve » hieu va, hieu van
vi ve » va ve, gi ve, ve ve

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 ((da lang) OR (va lang)) xa hoi. hieu ve ((cam thuc) or (nam thuc)) va hanh vi ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((da lang) OR (va lang)) xa hoi. hieu ve ((cam thuc) OR (nam thuc)) va hanh vi ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((da lang) OR (va lang)) xa hoi. hieu ve ((cam thuc) or (nam thuc)) va hanh vi ve triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((da lang) OR (va lang)) xa hoi. hieu ve ((cam thuc) or (nam thuc)) va hanh vi ve triet*.