Perhaps you should try some spelling variations:
nghien cua » nghien cuu, nghiep cua, nghiep vua
cach thoi » cac thoi, cach thuc, cach noi
thoi tap » toi tap, hoc tap, thoi dai
hoa toan » hoa tan, hop toan, hoa than
khoa hoc » hoa hoc
nhan dan » phan dau, gian dan, nhan tai
so cach » so sach, co cach, loi cach
hoc xua » hoc cua, hoc xa, hoc lua
xua hai » qua hai, cua hai, xa hai
hai van » thai van, ha van, hai tan
cua ha » cua nha, cua cha, chua ha
ha hoa » hai hoa, kha hoa, nha hoa

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

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