Theodore Presser Company : The original publisher. You can find the piano reduction and study score here .
The is a more recent work (premiered in 2024) that follows a similar virtuosic tradition . Score & Materials liebermann concerto flute pdf link
Flute Center of New York : Provides the Op. 39 Flute and Piano reduction : Lowell Liebermann Theodore Presser Company : The original publisher
Since this is a standard repertoire piece, physical scores (or digital versions from authorized retailers) are widely available: liebermann concerto flute pdf link