Currently, thirty-four samarium, thirty-four europium, thirty-one gadolinium, and thirty-one terbium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.
@article{arxiv.1201.4159,
title = {Discovery of Samarium, Europium, Gadolinium, and Terbium Isotopes},
author = {E. May and M. Thoennessen},
journal= {arXiv preprint arXiv:1201.4159},
year = {2015}
}