Complex sentence: Photographs of Pibulsonggram were to be found everywhere (in turn, those of the abdicated King Prajadhipok were banned), his slogans appeared in newspapers, were plastered on billboards and repeated over the radio.
Split into simpler sentences: Photographs of Pibulsonggram were to be found everywhere and those of the abdicated King Prajadhipok were banned. His quotes appeared in newspapers, were plastered on billboards and repeated over the radio.