Der Perlentaucher unter den Buchläden Eichendorff21

René Erlín Castillo obtained his PhD from Ohio University. He has been professor in Universidad de Oriente, Venezuela, Visiting Professor in Ohio University and nowadays he is a professor in the Universidad Nacional de Colombia. His research, spread across around 50 papers, is done mainly in functional analysis, real analysis, complex analysis, harmonic analysis, operator theory, potential theory and partial Differential Equations. He has authored a book and a textbook both in Spanish. Humberto Rafeiro received his PhD from _Algarve University, Portugal_ and did postdoctoral work in the research group _Centro de Análise Funcional e Aplicações_ in the _Instituto Superior Técnico, Universidade de Lisboa, Portugal_. Nowadays he is a professor in the _Pontifical Universidad Javeriana_. His research interests range from harmonic analysis, function spaces, operator theory in non-standard function spaces, potential type operators, hypersingular integrals and fractional calculus, having published near 40 papers on these subjects. He has co-authored a textbook in Spanish.