Perhaps you should try some spelling variations:
sach tranh » canh tranh
tranh thuc » trinh thuc, trang thuc, thanh thuy
khoan pho » khoan nhoi, khoan phai, khoan hoi
thuc dac » thuoc dac, thuc dan, thuc day
dac khoa » da khoa, dai khoa, dau khoa
dinh tri » chinh tri
te sach » toc sach
khoa he » hoa he, khoa hoc, khong he
so dinh » do dinh, co dinh, so sinh
tue cac » tu cac, tuc cac, te cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( te sach tranh thuc dac khoa he thong ) or ( so dinh tri tue cac khoan pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach tranh thuc dac khoa he thong ) OR ( so dinh tri tue cac khoan pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( te sach tranh thuc dac khoa he thong ) or ( so dinh tri tue cac khoan pho thong ))*.