Rinaldo is an opera by George Frideric Handel, composed in 1711, and was the first Italian language opera written specifically for the London stage. Here is an arrangement for Cello and Piano accompaniment for the popular piece Lascia ch'io pianga (Almirena  act 2).  
With downloadable mp3 for audio help.  Six pages (4 page Cello and Piano and 2 pages Cello), 4:20' min.
Early Intermediate.

The String Quartet No. 21 in D major, K. 575, was written in June 1789 by Wolfgang Amadeus Mozart.
Here is an arrangement for Cello and Piano for the third Movement (menuetto and trio).

With downloadable mp3 for audio help.
Eleven pages (5 pages both Cello and Piano, 3 pages Piano part, 3 pages Cello part), 6:30' min.

Intermediate.
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also check:
Air de Rinaldo Cello Piano duet : SheetMusicPlus number 20448368
Adagio Cantabille op13 Beethoven Cello Piano duet : SheetMusicPlus number 20447640
A minuet sonatine for Cello and Piano duet pdf mp3 : SheetMusicPlus number 20069947

Ludwig van Beethoven's Piano Sonata No. 8 in C minor, Op. 13, commonly known as Sonata Pathétique, was written in 1798 when the composer was 27 years old, and was published in 1799. It has remained one of his most celebrated compositions.
Here is an arrangement for Cello and Piano accompaniment for Adagio Cantabille (op.13-II).
With downloadable mp3 for audio help.  Eight pages (6 page Cello and Piano and 2 pages Cello), 3:56' min.