Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
danh hai » dang hai, lanh hai, manh hai
cao thuc » cao thuoc, bao thuc, can thuc
hai cua » thai cua, dai cua, hoi cua
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
ty nang » ky nang, ty xang, ty hang
va cao » va cac, va co, va dao
x hoi » xa hoi, x ho, 5 hoi
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: ((te sach) or (toc sach)) ty nang ((x hoi) OR (o hoi)). lieu va cao thuc va danh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty nang ((x hoi) OR (o hoi)). lieu va cao thuc va danh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ty nang ((x hoi) OR (o hoi)). lieu va cao thuc va danh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ty nang ((x hoi) OR (o hoi)). lieu va cao thuc va danh hai cua tre*.