7
Published 1875
Book
8
Published 1875
Book
9
Published 1897
Zettel
Book
12
Published 1904
Book
13
Published 1905
Book
14
Published 1907
Book
15
Published 1911
Book
16
Published 1912
Book
17
Published 1912
Book
18
Published 1925
Zettel
Book
19
Published 1928
Book
20
Published 1931
Book