Perhaps you should try some spelling variations:
kham thong » khap thong, khau thong, pham thuong
sach tren » sach tien, sach tranh
tren thuc » trien thuc, tron thuc, trinh thuc
hanh khoa » hang khoa, anh khoa, hanh hoa
khoa kham » kho khan, khoa than
toc sach » hoc sach, doc sach, thuoc sach
sach tri » sach tai, sach truc, sach bai
tri tuc » tri thuc, tri tue, tri tac
tuc cac » tu cac, tich cac
cac hoa » cac hoat, cac khoa, cau hoa

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

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