If you are a student or faculty member at a university with a music department, your library likely has a subscription to or Naxos Sheet Music . You can often download a Ligeti Etude PDF for free through the library’s portal for academic use.
If you are a student, most music conservatories hold these scores in their physical or digital archives (often via services like nkoda ). Technical Challenges ligeti etude pdf
If you are looking for the sheet music for György Ligeti's Piano Études If you are a student or faculty member