Looking for the font appearing on the cover of Rilke Poems 1906 - 26 (1957) - thank you for your help.

Not a font. That is hand-drawn. 

What Ralf said.

There are several typefaces based on similar styles of lettering (a few examples: Post-Antiqua, Amanda, Scriptuale, Altra), however none will have the exact same features of the samples, such as the Uncial-inspired |R|. On that front, Korigan could offer an alternative.

Thank you again for your help and sharing alternatives.