Javier, A. M., Kreft, O., Alberola, A. P., Kirchner, C., Zebli, B., Susha, A. S., Horn, E., Kempter, S., Skirtach, A. G., Rogach, A. L., Radler, J., Sukhorukov, G. B., Benoit, M., & Parak, W. J. (2006). Combined atomic force microscopy and optical microscopy measurements as a method to investigate particle uptake by cells. Small, 2(3), 394-400. doi:10.1002/smll.200500282.