Perepichka, D., Perepichka, I., Popov, A., Bryce, M., Batsanov, A., Chesney, A., …Sokolov, N. (2001). Electron acceptors of the fluorene series. Part 12. 9- (Metalloceneylidene)nitrofluorene derivatives of Fc-NF, NF-Fc- NF, and NF-Rc-NF types, and the vinylogues Fc-pi-NF: synthesis, characterisation, intramolecular charge transfer, redox properties and X-. Journal of Organometallic Chemistry, 637, 445-462