Perhaps you should try some spelling variations:
doanh khoa » toan khoa
tai doanh » trai doanh, tri doanh, lai doanh
khoa phan » hoa phan, khoa than, khoa phau
phan tong » phan trong, phan cong, han tong
cach thuc » anh thuc, cac thu
thuc thuc » hoc thuc
thuc xuan » thuc huan, thuc luan, thuoc luan
xuan khoa » luan khoa, xuat khoa, quan khoa
cac tren » ca tren, cau tren, rac tren
tren tai » tren thi, tren vai, tien tai
thu cach » thuc cach, thu canh, tu cach
khoa he » hoa he, khoa hoc, khong he
thong » trong

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu cac tren tai doanh khoa phan tong ) or ( thu cach thuc thuc xuan khoa he thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu cac tren tai doanh khoa phan tong ) OR ( thu cach thuc thuc xuan khoa he thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu cac tren tai doanh khoa phan tong ) or ( thu cach thuc thuc xuan khoa he thong ))*.