Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
danh lai » danh sai, gianh lai, dinh lam
hieu va » lieu va, hieu qua
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet
xuc va » tuc va, luc va, xac va
x hoi » xa hoi, o hoi, x ho

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 (doc sach)) ky nang x hoi. hieu va cac ((xuc va) or (duc va)) danh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) ky nang x hoi. hieu va cac ((xuc va) OR (duc va)) danh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ky nang x hoi. hieu va cac ((xuc va) or (duc va)) danh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky nang x hoi. hieu va cac ((xuc va) or (duc va)) danh lai cua tre*.