Perhaps you should try some spelling variations:
khan thong » khap thong, khau thong, nhan thong
thuoc cac » thuoc cuc, thuoc cao, thuoc dac
pho thong » he thong
sach tri » sach tai, sach tren, sach truc
sinh kho » sinh khoa, sinh khoi, sinh kha
kho khan » khoa kham, khoa than
tu thuoc » truc thuoc, tu thuong, cua thuoc
te sach » toc sach
tri hoc » triet hoc, tri thuc, thai hoc
tu cach » tu cac
cach tu » cach thuc
cac doi » cac dai, cac toi, cau doi

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 tri hoc sinh kho khan thong ) or ( tu cach tu thuoc cac doi pho thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach tri hoc sinh kho khan thong ) OR ( tu cach tu thuoc cac doi pho thong )).
• Adding a wildcard symbol may retrieve word variants: (( te sach tri hoc sinh kho khan thong ) or ( tu cach tu thuoc cac doi pho thong ))*.