Interchangeable ch/sh and k/t characters

[Mauro]

I insist that this claim holds only for texts of the same type, namely texts that consist mostly of discursive or narrative prose -- like novels, chronicles, philosophical treatises, newspaper and magazine articles, even textbooks.  Like all the books in your example.  

I'm sorry Jorge, but I cannot agree with you, in fact my example uses a very diverse panel of texts.

Enzo Biagi, L'albero dai fiori bianchi, I guess a novel (did not read it), 1994
Italo Calvino, Il Barone rampante, 'fantasy' novel, 1957
Alessandro Baricco, Seta, novel, 1996
Edmondo de Amicis, Cuore, novelettes, ~1880
Ugo Foscolo, Notizie intorno a Didimo Chierico, I don't know, ~1810
Giacomo Leopardi, Canti, poetry, 1817-1836
Giordanio Bruno, La cena delle ceneri, philosophical dialogue, ~1583
Dante, Divina Commedia Inferno, poetry, 1304-1321
Carlo Goldoni, L'avaro, theatrical comedy, 1756
Eugenio Barbarich, La campagna del 1796 in Veneto, military history, 1910
Vittorio Alfieri, Della tirannide, political treatise, 1777
Appunti di anatomia, anonymous, notes from anatomy lessons, ?? 1970-2010 ??
Vittorio Alfieri, Bruto secondo, theatrical tragedy, 1789
Declration of human rights, Italian, ??
L'amore di Loredana, Luciano Zuccoli, novel, 1908

Notwithstanding the temporal span (almost 700 years!), the difference in genre (prose, poetry, theater), the difference in topics, the orthographical differences (I don't need the late medieval Dante here: for instance Italian used to have a diphtong 'uo' [uo] which has, since say ~1920, been replaced by 'o' [ɔ] in most words; or, the letter 'j' was used for the semi-vowel [j] while now the orthography uses 'i'), the lexical differences, the linguistical differences, in spite of all this just the bigrams statistic is enough to positively identify a text as Italian or not.

But yet again: if you feel my panel of texts is not diverse enough and have a different one to propose, in any language, link me the documents (.txt possibly) and I'll check.