Perhaps you should try some spelling variations:
khoan kham » khoa kham, khoanh khac, khoan cam
kham thong » khap thong, khau thong, pham thuong
khoa toan » khoa than, hoa toan, khoa luan
cach thuc » anh thuc, cac thu
thuc thac » thuc thuc, thuc thai, thuc khac
sach tri » sach tai, sach tren, sach truc
tri thuc » tri tue
thuc cac » thuc cach, tuc cac, phuc cac
cac khoa » cac khoi, dac khoa, cao khoa
thac cac » thoai cac, thanh cac, thuc cach
tu sach » thu sach, su sach, te sach
te cach » ve cach, te sach, tu cach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach tri thuc cac khoa toan thong ) or ( te cach thuc thac cac khoan kham thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tri thuc cac khoa toan thong ) OR ( te cach thuc thac cac khoan kham thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tri thuc cac khoa toan thong ) or ( te cach thuc thac cac khoan kham thong ))*.