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