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 » so sach, vu sach
hieu ve » hieu va, hieu van
doi cua » dai cua, hoi cua
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
ve cam » ve cham, ve cac, va cam
di cua » dai cua, de cua, do cua
o hoi » co hoi, o hoc, o hai

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 o hoi. hieu ve cam thuc ((vat hanh) or (van hanh)) ((di cua) or (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang o hoi. hieu ve cam thuc ((vat hanh) OR (van hanh)) ((di cua) OR (doi cua)) tre.
• Adding a wildcard symbol may retrieve word variants: su sach y nang o hoi. hieu ve cam thuc ((vat hanh) or (van hanh)) ((di cua) or (doi cua)) tre*.