Hutloff, A., Dittrich, A. M., Beier, K. C., Eljaschewitsch, B., Kraft, R., Anagnostopoulos, I., & Kroczek, R. A. (1999). ICOS is an inducible T-cell co-stimulator structurally and functionally related to CD28. Nature, 402, 21-24.
Quiroga, M. F., Pasquinelli, V., Martinez, G. J., Jurado, J. O., Zorrilla, L. C., Musella, R. M., ... & Garcia, V. E. (2006). Inducible costimulator: a modulator of IFN-γ production in human tuberculosis. The Journal of Immunology, 176(10), 5965-5974.
Buonfiglio, D., Bragardo, M., Redoglia, V., Vaschetto, R., Bottarel, F., Bonissoni, S., ... & Dianzani, U. (2000). The T cell activation molecule H4 and the CD28-like molecule ICOS are identical. European journal of immunology, 30(12), 3463-3467.