Possible solutions of measurement problem

collapse theories - Unified dynamics for microscopic and macroscopic systems - G. C. Ghirardi, A. Rimini, and T. Weber

2006 Irreversibility in Collapse-Free Quantum Dynamics and the Second Law of Thermodynamics M. B. Weissman

https://en.wikipedia.org/wiki/Penrose_interpretation

Roger Penrose - What Does Quantum Theory Mean?

Freeman Dyson posits "QM cannot be a complete description of nature" @ J.A. Wheeler's 90th birthday

Jeremy Bernstein - Abstract: This is a letter of inquiry about the nature of quantum mechanics

emergent QM - The Cellular Automaton Interpretation of Quantum Mechanics

Gerard 't Hooft: Physics on the Boundary between Classical and Quantum Mechanics (EmQM13)

nonlinear QM

Precision Tests of Quantum Mechanics - Steven Weinberg

David Bohm - pilot wave

https://en.wikipedia.org/wiki/Leggett%E2%80%93Garg_inequality

2002 Testing the limits of quantum mechanics: motivation, state of play, prospects