Perhaps you should try some spelling variations:
tham thuc » nham thuc, pham thuc, tam thuc
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
hieu ve » hieu va
sach ty » sach y, sach tu, sach thu
ty tang » tay tang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, me hoi
vi hoa » voi hoa, vi hoc, va hoa

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 tang ((ma hoi) or (ma hoa)). ((hieu ve) or (hieu van)) tham thuc van hanh vi hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty tang ((ma hoi) OR (ma hoa)). ((hieu ve) OR (hieu van)) tham thuc van hanh vi hoa viet.
• Adding a wildcard symbol may retrieve word variants: su sach ty tang ((ma hoi) or (ma hoa)). ((hieu ve) or (hieu van)) tham thuc van hanh vi hoa viet*.