Perhaps you should try some spelling variations:
xanh hanh » danh thanh, ban hanh, van hanh
thuc xanh » thuc hanh, thuc thanh, thuc dan
cam thuc » am thuc, nam thuc, cam thu
su sach » so sach
hanh de » hanh ve, hanh kem
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
ly nang » ky nang, ly hang, ly vang
vu sach » vu bach, vu khach
va cam » va cham, va cac, va cao
de cua » le cua, te cua, dieu cua
o hoi » co hoi, o hai, o hoa
o hoc » co hoc, mo hoc, so hoc

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