X-ray refractive planar lenses in combination with planar X-ray waveguide L.G. Shabel'nikov, A. Snigirev, I. Snigireva, S. Kuznetsov, V. Yunkin, V. Levashov et M. Grigoriev J. Phys. IV France, 104 (2003) 227-230 DOI: 10.1051/jp4:200300067