Preface: For the sake of simplicity, the works referred to will be cited with the number from the bibliography. The number following the slash indicates the respective page number. For example: 158 Volume 2/65 refers to page 65 of the second volume of number 158 in the bibliography, specifically the relevant page in Felix Klein's lectures on the development of mathematics in the 19th century. Ancestry. Youth in Russia: 1) Cf. among others 48b/17. 2) 168/12 f. 3) 177/35 f. 4) 180/24 f.; 179/469 ff. 5) 177. 6) On ancestry particularly 48b/9 ff.; 35/12 ff., 60; 177/25, 33 - 36, 44 f.; 93/4 ff.; 37/9 f. 7) 48b/17. 8) 173/23 f. 9) 168/4 f. 10) 35/30. 11) 168. 12) Cf. 35/24 f. 13) According to 35/100 and 37/60: Alexandra Alexandrowna Briullowa. 14) 25/397. 15) Frankfurt 1968, 3rd ed. 1987, first published in 1897. 16) Translated from the English edition.