Stockhausen, K - In Freundschaft (In Friendship)
The harmonics were proposed by Aurèle Nicolet to whom I had sent the manuscript. Only after the score had been printed, did I work with various flutists and realised that all harmonics may be dispensed with. In many harmonics I heard pitch and timbre changes that I did not like. The instruction "harmonics, always ad lib." thus makes it also possible, that one does not play any harmonics at all.