Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
dac nhan » cac nhan, danh nhan, ca nhan
day hanh » day nhanh, day thanh, dao hanh
sach ky » sac ky, sach ty, sach kem
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
de cua » le cua, te cua, dieu cua
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: su ((sach ky) OR (sach y)) nang x hoi. hieu ve cham thuc ((day hanh) or (dac nhan)) de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) nang x hoi. hieu ve cham thuc ((day hanh) OR (dac nhan)) de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach y)) nang x hoi. hieu ve cham thuc ((day hanh) or (dac nhan)) de cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach y)) nang x hoi. hieu ve cham thuc ((day hanh) or (dac nhan)) de cua tre*.