Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
thuc day » thuc dan, thuc vat
day hanh » day nhanh, day thanh, dao hanh
cua tre » cua te, cua triet, dua tren
hanh di » hanh vi, hanh de, hang di
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
ly nang » ky nang, ly hang, ly vang
cuu tre » cau tren, cau treo
ve cam » ve cham, ve cac, va cam
y nang » ky nang, v nang, may nang

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