Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
day nhanh » day thanh, duy nhanh, dac nhan
day hanh » day thanh, dao hanh, day manh
sach ly » sach y, sach lo, sach ty
vu sach » vu bach, su sach, vu khach
va cham » va chat, va tham
hieu va » lieu va, hieu qua
ly nang » ky nang, ly hang, ly vang
cua tre » cua te, cuu tre, cua triet
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 ly nang ((x hoi) OR (xa hoi)). hieu va cham thuc ((day hanh) or (day nhanh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ly nang ((x hoi) OR (xa hoi)). hieu va cham thuc ((day hanh) OR (day nhanh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ly nang ((x hoi) OR (xa hoi)). hieu va cham thuc ((day hanh) or (day nhanh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ly nang ((x hoi) OR (xa hoi)). hieu va cham thuc ((day hanh) or (day nhanh)) di cua tre*.