Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
y nang » ly nang, v nang, may nang
ve cam » ve cham, ve cac, va cam
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 va hanh vi ((cua tre) or (cuu 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 va hanh vi ((cua tre) OR (cuu 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 va hanh vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach ((y nang) OR (ky nang)) x hoi. hieu ve cam thuc va hanh vi ((cua tre) or (cuu tre))*.