Perhaps you should try some spelling variations:
dao thanh » ban thanh, tro thanh, de thanh
cam thuc » am thuc, nam thuc, cam thu
ban hanh » ban hang
sach ky » sac ky, sach y, sach ty
vu sach » vu bach, su sach, vu khach
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
di cua » dai cua, doi cua, de cua
x hoi » o hoi, x ho, 5 hoi

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