by Credner, Hermann; Kalkowsky, Ernst; Beck, Richard et al. , Published in Monatsberichte der Deutschen Geologischen Gesellschaft (1909)

by Schreiter, Rudolf; Beck, Richard; Stutzer, Otto et al. , 1906

by Gäbert, Carl; Beck, Richard , 1903

by Schalch, Ferdinand; Beck, Richard , 1897

by Beck, Richard , 1887

by Beck, Richard , 1884