Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
va thanh » gia thanh, va tinh, le thanh
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
cac tuc » cac toc, cac tac, cac nuoc
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
cac tu » cac thu, cach tu, cac du
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky dang xay hoi. hieu van ((cac tuc) OR (cac tu)) ((va thanh) or (ban thanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky dang xay hoi. hieu van ((cac tuc) OR (cac tu)) ((va thanh) OR (ban thanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky dang xay hoi. hieu van ((cac tuc) OR (cac tu)) ((va thanh) or (ban thanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky dang xay hoi. hieu van ((cac tuc) OR (cac tu)) ((va thanh) or (ban thanh)) vi cua tre*.