Meyer, L., Wildanger, D., Medda, R., Punge, A., Rizzoli, S., Donnert, G. and Hell, S. W.
Dual-color STED microscopy at 30-nm focal-plane resolution. Small 4: 1095-1100 (2008).

Stimulated emission depletion (STED) fluorescence microscopy images protein distribution in cells in two-color channels at a resolution of 30 nm in the focal plane (see image), corresponding to a seven-to eightfold improvement over confocal microscopy resolution.