Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
thanh de » hanh de, thanh ve, thanh do
hieu van » hieu va, thien van, lieu va
yu pang » yun pang, yu wang, yu jiang
cac luc » cau luc, cac nuoc, cac cuoc
yu hang » yu zhang, yu wang, thu hang
tu sach » thu sach, su sach, te sach
de cua » le cua, te cua, dieu cua

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 ((yu hang) OR (yu pang)) xa hoi. hieu van ((cac luc) or (coc luc)) gia thanh de cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((yu hang) OR (yu pang)) xa hoi. hieu van ((cac luc) OR (coc luc)) gia thanh de cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((yu hang) OR (yu pang)) xa hoi. hieu van ((cac luc) or (coc luc)) gia thanh de cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((yu hang) OR (yu pang)) xa hoi. hieu van ((cac luc) or (coc luc)) gia thanh de cua viet*.