Perhaps you should try some spelling variations:
cam thuc » am thuc, cam thu, can thuc
nam thuc » nam thuoc, am thuc, nam thu
vat hanh » vat thanh, van hanh, va hanh
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
y nang » ky nang, ly nang, v nang
di cuu » di cau, dinh cuu
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.

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