Perhaps you should try some spelling variations:
day nhanh » day thanh, duy nhanh, dac nhan
day hanh » day thanh, dao hanh, day manh
cam thuc » am thuc, nam thuc, cam thu
vu sach » vu bach, su sach, vu khach
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
ve cam » ve cham, ve cac, va cam
co hoi » co hoc, co loi
cua te » cua tu
o hoi » o hoc, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang ((o hoi) OR (co hoi)). hieu ve cam thuc ((day hanh) or (day nhanh)) dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ((o hoi) OR (co hoi)). hieu ve cam thuc ((day hanh) OR (day nhanh)) dai cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ((o hoi) OR (co hoi)). hieu ve cam thuc ((day hanh) or (day nhanh)) dai cua te*".