Perhaps you should try some spelling variations:
khoi thanh » hoi thanh, khoan thanh, khong thanh
cach thoi » cac thoi, cach thuc, cach noi
dong khoi » dang khoi, dong hoi, dong khoa
thanh hoa » thanh pho
thoi tap » toi tap, hoc tap, thoi dai
cuu dong » cuu cong, cuu tong, cuu long
nhan dan » phan dau, gian dan, nhan tai
tu cach » tu cac
hai van » thai van, hai tan, hao van
hoc xa » hoc ma
ha van » hoa van, nha van, va van

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cach thoi tap, nghien cuu dong khoi thanh hoa hoc xa ((hai van) or (ha van)) nhan dan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cach thoi tap, nghien cuu dong khoi thanh hoa hoc xa ((hai van) OR (ha van)) nhan dan.
• Adding a wildcard symbol may retrieve word variants: tu cach thoi tap, nghien cuu dong khoi thanh hoa hoc xa ((hai van) or (ha van)) nhan dan*.