Historical clue formulations

• Subject of a classic black, white and red poster — 2020-09-18
• Subject of "Guerrillero Heroico" — 2015-09-20
• Who said "If you tremble with indignation at every injustice, then you are a comrade of mine" — 2015-09-11
• "Guerrilla Warfare" author, 1961 — 2008-10-25