expérience d'Eötvös
1989 / Actually, Eötvös did publish his results in 1910, it's just that no one knows about it... / Michael Martin Nieto ; Richard J. Hughes ; T. Goldman / American Journal of Physics 57 (1989) p. 397 [doi]
1999 / [Search and Discovery] Gravitational Self-Energy and the Equivalence Principle / Bertram Schwarzchild / Physics Today 52 (1999) p. 19 [doi]