Perhaps you should try some spelling variations:
day nhanh » day thanh, duy nhanh, dac nhan
cam thuc » am thuc, nam thuc, cam thu
day hanh » day thanh, dao hanh, day manh
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
y nang » ly nang, v nang, may nang
ve cam » ve cham, ve cac, va cam
di cua » dai cua, doi 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 ((y nang) OR (ky nang)) x hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((y nang) OR (ky nang)) x hoi. hieu ve cam thuc ((day hanh) OR (day nhanh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((y nang) OR (ky nang)) x hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) OR (ky nang)) x hoi. hieu ve cam thuc ((day hanh) or (day nhanh)) di cua tre*.