Perhaps you should try some spelling variations:
day nhanh » day thanh, duy nhanh, dac nhan
cam thuc » am thuc, nam thuc, cam thu
dinh cuu » dinh chi
day hanh » day thanh, dao hanh, day manh
sach ky » sach y, sach ty, sach kem
cuu tre » cua tre, cau tren, cau treo
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
sac ky » cac ky, sai ky
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo ((sach ky) OR (sac ky)) nang x hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) dinh cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo ((sach ky) OR (sac ky)) nang x hoi. hieu ve cam thuc ((day hanh) OR (day nhanh)) dinh cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo ((sach ky) OR (sac ky)) nang x hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) dinh cuu tre".
• Adding a wildcard symbol may retrieve word variants: bo ((sach ky) OR (sac ky)) nang x hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) dinh cuu tre*.