Perhaps you should try some spelling variations:
day hanh » day nhanh, day thanh, dao hanh
thuc day » thuc dan, thuc vat
cam thuc » am thuc, nam thuc, cam thu
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
mang xa » lang xa, mang may, dang xay
nang ma » tang ma, sang ma, nang cao
ve cam » ve cham, ve cac, va cam
di cua » doi cua, de cua, do cua

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 ((mang xa) or (nang ma)) hoi. hieu ve cam thuc day hanh ((di cua) OR (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((mang xa) OR (nang ma)) hoi. hieu ve cam thuc day hanh ((di cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y ((mang xa) or (nang ma)) hoi. hieu ve cam thuc day hanh ((di cua) OR (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: su sach y ((mang xa) or (nang ma)) hoi. hieu ve cam thuc day hanh ((di cua) OR (dai cua)) tre*.