The signatories / publishing groups of this poster are:

Hangzhou Revolutionary Rebel United Headquarters of the Propaganda and Literature Defense System (杭州市宣传文卫系统革命造反联合总部)
Hangzhou Revolutionary Rebel Headquarters of Literary and Art Circles to Defend Mao Zedong Thought (杭州市文艺界捍卫毛泽东思想革命造反总部)
Hangzhou Red Revolutionary Rebel Headquarters of the Work (杭州市工农兵美术工作团红色革命造反总部)
Hangzhou Revolutionary Rebel Headquarters of the Culture Education Office (杭州市文化教育局革命造反总部)
Hangzhou Revolutionary Rebel Headquarters of the Propaganda Section of the Revolutionary Committee (杭州市委宣传部革命造反总部)
Hangzhou Revolutionary Rebel Headquarters of New China Book Stores (杭州市新华书店革命造反总部)