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 y, sach kem
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
te cua » tue cua, le cua, de 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 ty)) nang x hoi. hieu ve cham thuc ((day hanh) or (dac nhan)) te cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang x hoi. hieu ve cham thuc ((day hanh) OR (dac nhan)) te cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) nang x hoi. hieu ve cham thuc ((day hanh) or (dac nhan)) te cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach ty)) nang x hoi. hieu ve cham thuc ((day hanh) or (dac nhan)) te cua tre*.