Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
cam thuc » am thuc, nam thuc, cam thu
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
hanh y » hanh ky, anh y, hanh _
sanh y » sinh y, anh y, sach y
ve cam » ve cham, ve cac, va cam
vi hoa » voi hoa, va hoa, bi hoa
vi hoc » li hoc, va hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: so ((sanh y) or (hanh y)) nang cao hoi. hieu ve cam thuc vat hanh ((vi hoa) OR (vi hoc)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so ((sanh y) OR (hanh y)) nang cao hoi. hieu ve cam thuc vat hanh ((vi hoa) OR (vi hoc)) viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so ((sanh y) or (hanh y)) nang cao hoi. hieu ve cam thuc vat hanh ((vi hoa) OR (vi hoc)) viet*".