Lévy-Leblond, J. (1977). "On the conceptual nature of the physical constants". La Rivista del Nuovo Cimento. Series 2. 7 (2): 187–214. Bibcode:1977NCimR...7..187L. doi:10.1007/bf02748049. S2CID121022139.Lévy-Leblond, J.-M. (1979). "The importance of being (a) Constant". In Toraldo di Francia, G. (ed.). Problems in the Foundations of Physics, Proceedings of the International School of Physics 'Enrico Fermi' Course LXXII, Varenna, Italy, July 25 – August 6, 1977. New York: NorthHolland. pp. 237–263.
Lévy-Leblond, J. (1977). "On the conceptual nature of the physical constants". La Rivista del Nuovo Cimento. Series 2. 7 (2): 187–214. Bibcode:1977NCimR...7..187L. doi:10.1007/bf02748049. S2CID121022139.Lévy-Leblond, J.-M. (1979). "The importance of being (a) Constant". In Toraldo di Francia, G. (ed.). Problems in the Foundations of Physics, Proceedings of the International School of Physics 'Enrico Fermi' Course LXXII, Varenna, Italy, July 25 – August 6, 1977. New York: NorthHolland. pp. 237–263.
Lévy-Leblond, J. (1977). "On the conceptual nature of the physical constants". La Rivista del Nuovo Cimento. Series 2. 7 (2): 187–214. Bibcode:1977NCimR...7..187L. doi:10.1007/bf02748049. S2CID121022139.Lévy-Leblond, J.-M. (1979). "The importance of being (a) Constant". In Toraldo di Francia, G. (ed.). Problems in the Foundations of Physics, Proceedings of the International School of Physics 'Enrico Fermi' Course LXXII, Varenna, Italy, July 25 – August 6, 1977. New York: NorthHolland. pp. 237–263.