Perhaps you should try some spelling variations:
thuoc quen » thuoc quyen, thuoc tren, thuc que
dung thoi » dung thi, dung toi, dung thong
quen vang » quan van, que van, que lang
tac trung » trac trung, tai trung, tac trong
trung hoc » trung quoc
tac dung » sach dung, xay dung, tin dung
dung hoc » dong hoc, dung khoa, dung cho
hoc mon » hoc moi, hoc mot, hoc cong
hoc mo » hoc moi, hoc mot, hoc ma

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( dung thoi quen vang. tac trung hoc mo ) or ( dung thuoc quen vang. tac dung hoc mon ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( dung thoi quen vang. tac trung hoc mo ) OR ( dung thuoc quen vang. tac dung hoc mon )).
• Adding a wildcard symbol may retrieve word variants: (( dung thoi quen vang. tac trung hoc mo ) or ( dung thuoc quen vang. tac dung hoc mon ))*.