This book addresses the basic physical phenomenon of small-angle scattering (SAS) of neutrons, x-rays or light from complex
hierarchical nano- and micro-structures. The emphasis is on developing theoretical models for the material structure containing
self-similar or fractal clusters. Within the suggested framework, key approaches for extracting structural information from
experimental scattering data are investigated and presented in detail. The range of parameters which can be obtained pave
the road towards a better understanding of the correlations between geometrical and various physical properties (electrical,
magnetic, mechanical, optical, dynamical, transport etc.) in fractal nano- and micro-materials.