@article{SJ_1961-1962__5__A8_0,
     author = {Pirani, F. A. E. and Williams, Gareth},
     title = {Rigid motion in a gravitational field},
     journal = {S\'eminaire de m\'ecanique analytique et de m\'ecanique c\'eleste},
     note = {talk:8-9},
     pages = {1--16},
     year = {1961-1962},
     publisher = {Secr\'etariat math\'ematique},
     volume = {5},
     zbl = {0112.43904},
     language = {en},
     url = {https://www.numdam.org/item/SJ_1961-1962__5__A8_0/}
}