Perhaps you should try some spelling variations:
khan thong » khap thong, khau thong, nhan thong
tham thuy » thai thuy, pham thuy, thac thuy
thuy sinh » thuy linh, huy sinh, thuy tinh
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
hoc thong » hoc thuong, hoc trong, hoc hong
cac tham » cac ham, sach tham, cac thanh
sinh kho » sinh khoa, sinh khoi, sinh kha
kho khan » khoa kham, khoa than
thu sach » tu sach, thuat sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
dan hoa » danh hoa, dan hoat, dan khoa

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 tham thuy sinh kho khan thong ) or ( thu sach tren thuc dan hoa hoc thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu cac tham thuy sinh kho khan thong ) OR ( thu sach tren thuc dan hoa hoc thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu cac tham thuy sinh kho khan thong ) or ( thu sach tren thuc dan hoa hoc thong ))*.