Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
danh dai » danh dau, danh di, danh sai
trung va » truong va, trang va, trung ha
van chat » cao chat
ly hang » ly quang
truc va » thuc va, thuc vat
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((y nang) or (ly hang)) xa hoi. hieu van chat ((truc va) OR (trung va)) danh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((y nang) OR (ly hang)) xa hoi. hieu van chat ((truc va) OR (trung va)) danh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((y nang) or (ly hang)) xa hoi. hieu van chat ((truc va) OR (trung va)) danh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ((y nang) or (ly hang)) xa hoi. hieu van chat ((truc va) OR (trung va)) danh dai cua tre*.