Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
cac thuc » cach thuc, cac thu, can thuc
vu khach » vu khanh, vu khac, vay khach
vuc nang » cuc nang, vu nang, chuc nang
va thanh » ban thanh, va tinh, le thanh
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
ma hoi » mai hoi, xa hoi, ma hoa
do va » do van, so 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) or (vu khach)) vuc nang ma hoi. hieu ve cac thuc ((va thanh) OR (gia thanh)) do va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu khach)) vuc nang ma hoi. hieu ve cac thuc ((va thanh) OR (gia thanh)) do va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu khach)) vuc nang ma hoi. hieu ve cac thuc ((va thanh) OR (gia thanh)) do va triet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu khach)) vuc nang ma hoi. hieu ve cac thuc ((va thanh) OR (gia thanh)) do va triet*.