This section contains preprints published on the Internet — on the present platform and on ResearchGate. The major contribution to the project, the book, has two versions — English and Polish — but the other contributions are only in English. All remarks, advises and comments will be highly appreciated and should be addressed to Ten adres pocztowy jest chroniony przed spamowaniem. Aby go zobaczyć, konieczne jest włączenie w przeglądarce obsługi JavaScript..pl.