Piazzolla's works will not enter the public domain in standard 70-year jurisdictions until January 1, 2063 . What You Will Find on IMSLP
Because it is a protected work, you can find legitimate copies through the following channels: libertango piazzolla imslp
Astor Piazzolla’s Libertango and the IMSLP: A Guide for Musicians and Researchers Piazzolla's works will not enter the public domain
Academic and large public libraries often hold physical copies of the Libertango score within collected tango anthologies. libertango piazzolla imslp
If you are a teacher in the US and need the original manuscript for academic analysis, a VPN server located in Canada will allow IMSLP to serve the download button. Note: This is for personal study; you cannot publicly perform the copyrighted original in the US without paying licensing fees to Warner/Chappell Music.