James R. Morrison is a writer and former orchestral librarian who has seen one too many students fail an audition due to a missing page from a pirated scan.
While Sancan is likely too modern for "public domain" (which usually applies to composers who died over 70 years ago), you can check the IMSLP site for any specific, publisher-authorized free editions. However, you will likely find that this work is protected. sancan flute sonatine pdf free work
It is a common habit for modern musicians to look for free sheet music online. While public domain works (published before 1929) are freely available on sites like IMSLP, the James R