
Source: Lectures on Quantum Mechanics (2012, 2nd ed. 2015), Ch. 3: General Principles of Quantum Mechanics
The close of his Nobel lecture: "The Statistical Interpretations of Quantum Mechanics" (11 December 1954) http://nobelprize.org/nobel_prizes/physics/laureates/1954/born-lecture.html
Context: Can we call something with which the concepts of position and motion cannot be associated in the usual way, a thing, or a particle? And if not, what is the reality which our theory has been invented to describe?
The answer to this is no longer physics, but philosophy. … Here I will only say that I am emphatically in favour of the retention of the particle idea. Naturally, it is necessary to redefine what is meant. For this, well-developed concepts are available which appear in mathematics under the name of invariants in transformations. Every object that we perceive appears in innumerable aspects. The concept of the object is the invariant of all these aspects. From this point of view, the present universally used system of concepts in which particles and waves appear simultaneously, can be completely justified. The latest research on nuclei and elementary particles has led us, however, to limits beyond which this system of concepts itself does not appear to suffice. The lesson to be learned from what I have told of the origin of quantum mechanics is that probable refinements of mathematical methods will not suffice to produce a satisfactory theory, but that somewhere in our doctrine is hidden a concept, unjustified by experience, which we must eliminate to open up the road.
Source: Lectures on Quantum Mechanics (2012, 2nd ed. 2015), Ch. 3: General Principles of Quantum Mechanics
"Einstein-Podolsky-Rosen Experiments", included in Speakable and Unspeakable in Quantum Mechanics (1987), p. 82 https://books.google.com/books?id=FGnnHxh2YtQC&pg=PA82
Aerts, D. (1998). " The entity and modern physics: the creation-discovery view of reality. http://www.vub.ac.be/CLEA/aerts/publications/1998EntModPhys.pdf" In E. Castellani (Ed.), Interpreting Bodies: Classical and Quantum Objects in Modern Physics (pp. 223-257). Princeton: Princeton University Press.
[1928, April 14, Introduction to Niels Bohr's The quantum postulate and recent developments of quantum theory, Nature, Suppl. No. 3050, 6, 52] As quoted by K. V. Laurikainen, The Origin and Development of the Idea of Complementarity, 1980.
Source: The mechanization of the world picture, 1961, p. 499
in The Quantum Theory and Reality, by [Bernard d'Espagnat, Scientific American, November, 1979, 158] http://www.sciam.com/media/pdf/197911_0158.pdf
Does quantum mechanics carry the seeds of its own destruction? (1991)
The Problems of Quantum Mechanics: Steven Weinberg https://www.youtube.com/watch?v=mBninatwq6k (July 17, 2018) YouTube video at 3:58 of 45:42
Introduction, The Nature of Probability Theory, p. 3.
An Introduction To Probability Theory And Its Applications (Third Edition)