Grigull, P., Hildebrandt, D., Sardei, F., Feng, Y., Herre, G., Herrmann, A., et al. (1997). Experimental study on highly collisional edge plasmas in W7-AS island divertor configurations. Journal of Nuclear Materials, 241-243, 935-940. doi:10.1016/S0022-3115(96)00635-6.