Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van chat » cao chat
danh dai » danh dau, danh di, danh sai
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
truc va » thuc va, trung va
cua tre » cua te, cuu tre, cua triet

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