Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
danh dai » danh dau, danh di, danh sai
hieu van » hieu va, thien van, lieu va
van chat » cao chat
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
tu sach » thu sach, su sach, te sach
soc va » hoc va, loc va, goc va
doc va » duoc va, hoc va, duc va

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

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