Perhaps you should try some spelling variations:
day nhanh » day thanh, duy nhanh, dac nhan
cam thuc » am thuc, nam thuc, cam thu
sach thu » sach thue, sach thieu, sach tham
day hanh » day thanh, dao hanh, day manh
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, xach tay
ve cam » ve cham, ve cac, va cam
nang o » nang co, nang ho, nang ro
cua te » cua tu
o hoi » co hoi, o hoc, o hai

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 ty) OR (sach thu)) nang o 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 ty) OR (sach thu)) nang o 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 ty) OR (sach thu)) nang o hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) dai cua te*".