BK::BK(int identifier, std::string title, std::string author, int year, std::string publisher, int nb_pages): Ref(identifier, title, author, year) { this->publisher = publisher; this->nb_pages = nb_pages; } Art::Art(int identifier, std::string title, std::string author, int year, std::string journal, int start_page, int end_page): Ref(identifier, title, author, year) { this->journal = journal; this->start_page = start_page; this->end_page = end_page; } Ref:: Ref(int identifier, std::string title, std::string author, int year) { this->identifier = identifier; this->title = title; this->author = author; this->year = year; } void Manager::print() { std::cout publisher = publisher; this->nb_pages = nb_pages; } Art::Art(int identifier, std::string title, std::string author, int year, std::string journal, int start_page, int end_page): Ref(identifier, title, author, year) { this->journal = journal; this->start_page = start_page; this->end_page = end_page; } Ref:: Ref(int identifier, std::string title, std::string author, int year) { this->identifier = identifier; this->title = title; this->author = author; this->year = year; } void Manager::print() { std::cout