Perhaps you should try some spelling variations:
sach trien » sach tien, sach tren, sach thieu
trien hoat » tien hoa
dang khuan » khang khuan, dang khai, dang khanh
khoa thong » hoa thong, thoai thong, pho thong
thuoc sach » hoc sach, nuoc sach, thuat sach
sach khuan » sach khuyen, sach han, sach luan
hoat dang » hoat dong, hoat hang, hoang dang
tai thuoc » tri thuoc, bai thuoc, tac thuoc
toc sach » hoc sach, doc sach, nuoc sach
sach tai » sach bai, sach tham, sach dao
tu sach » thu sach, su sach, te sach

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 trien hoat dang khuan khoa thong ) or ( toc sach tai thuoc sach khuan khoa thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach trien hoat dang khuan khoa thong ) OR ( toc sach tai thuoc sach khuan khoa thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach trien hoat dang khuan khoa thong ) or ( toc sach tai thuoc sach khuan khoa thong ))*.