I would like to obtain a copy of the sheet music to the song Senza Fine.

Hello.

Sheet music for Alec Wilder's "Senza Fine" (also known as "The Phoenix
Love Theme") is available from Sheet Music Warehouse in the UK:
http://www.sheetmusicwarehouse.co.uk/cgi-bin/order.pl?stockref=10695

It's also available in the book "37 Italian Favorites: Great Songs of
the Century" listed at TomFolio.com:
http://www.tomfolio.com/bookdetails.asp?book=1703012

That book is also available used starting at around $7 on Amazon.com:
37 Italian Favorites: Great Songs of the Century
http://www.amazon.com/gp/product/offer-listing/0897244338/

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search strategy:
"senza fine" "sheet music"
wilder "senza fine" sheet

I hope this is the composition that you had in mind.  If not, please
let me know via the "request clarification" feature. Thanks.