[Madrid]: Agrupación Socialista del Puente de Vallecas / Partido Comunista de España Radio de Vallecas, 1937. First Edition. Broadside dated May 1, 1937, just four days after the bombing of Guernica, announcing a Popular Front alliance between the Communist Party and the Socialist Coalition of Madrid. Given its local character and the extremely fragile paper on which it is printed, an extremely rare example; OCLC gives a single location only (UCSD); not in COPAC, KVK, or European Library Database. Broadside, 43cm x 31cm (ca 17" x 12-1/2"). Printed in black on tan tissue-paper stock; text in two columns beneath headline; signed in print by Teodoro Medina (for the Socialist Coalition) and by Juan Muñoz (for the Communist Party). A few tiny nicks to extremities; single horizontal fold-line; Near Fine.