Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cac thuc » cach thuc, cac thu, can thuc
hieu ve » hieu va, hieu van
su sach » so sach, vu sach
ve cac » va cac, vien cac
y hang » ly hang, ty hang, yu hang
va hoi » va hoc, va hoa
doi va » hoi va, noi va, dai va
di va » dai va, di vao, di vat

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