@article{Burkhardt2021ApJLA, 
author = Burkhardt, A.M., Lee, K.L.K., Changala, P.B., Shingledecker, C.N., Cooke, I.R., Loomis, R.A., Wei, H., Charnley, S.B., Herbst, E., McCarthy, M.C., McGuire, B.A., 
title = Discovery of the pure polycyclic aromatic hydrocarbon indene ($c$-\ce{C9H8}), with GOTHAM observations of TMC-1, 
journal = Astrophysical Journal Lett., 
year = 2021, 
volume = 913, 
pages = 18 
}