Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
hieu van » hieu va, thien van, lieu va
thanh vi » hanh vi, thanh va, thanh ve
va thanh » gia thanh, ban thanh, va tinh
van dau » van dao, phan dau
dau xuc » dau xac, dau xua, dau nuoc
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc va
y nang » ky nang, ly nang, v nang
vi cua » vai cua, di 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: ((toc sach) OR (thuoc sach)) y nang ((x hoi) or (xa hoi)). hieu van dau xuc va thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) y nang ((x hoi) OR (xa hoi)). hieu van dau xuc va thanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (thuoc sach)) y nang ((x hoi) or (xa hoi)). hieu van dau xuc va thanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (thuoc sach)) y nang ((x hoi) or (xa hoi)). hieu van dau xuc va thanh vi cua tre*.