The Education of Henry Adams by Henry Adams: “He could not afterwards remember to have heard the name of Karl Marx mentioned, or the title of "Capital."”
The Uses of Literature by Italo Calvino: Cited as an example of books of revolutionary propaedeutics, from Marx's Capital to the manuals on guerrilla warfare
Bushido: The Soul of Japan by Inazo Nitobe: “More than a decade later, about the time that our feudalism was in the last throes of existence, Carl Marx, writing his "Capital," called the attention of his readers to the peculiar advantage of studying the social and political institutions of feudalism, as then to be seen in living form only in Japan.”