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