Tonnesen, J., Nadrigny, F., Willig, K. I., Wedlich-Söldner, R., & Nägerl, U. V. (2011). Two-color STED microscopy of living synapses using a single laser-beam pair. Biophysical Journal, 101(10), 2545-2552. doi:10.1016/j.bpj.2011.10.011.