Perhaps you should try some spelling variations:
cam thuc » nam thuc, cam thu, can thuc
vu sach » vu bach, su sach, vu khach
bo sach » co sach, hoc sach
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sach) or (bo sach)) ky nang ma hoi. hieu ve ((cam thuc) or (am thuc)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (bo sach)) ky nang ma hoi. hieu ve ((cam thuc) OR (am thuc)) va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (bo sach)) ky nang ma hoi. hieu ve ((cam thuc) or (am thuc)) va hanh vi cua tre*.