It was that companies talked about their products through advertisements on radio instead of buying advertising space in newspapers.

VOA: special.2011.04.14

When I was a boy there was one form and one form only and it was cartoon-- it was on Saturday morning cartoons and there was advertisements for foods on that and it was mainly for sugared cereals.

在我小时候有且只有一种形式,那就是动画,在周六早上的动画中,有关于食品的广告,主要是加糖麦片的广告

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

You don't see advertisements for participation in commercial real estate like this because the government would be on their backs if they did it.

你不会看到,投资商业地产DPP的广告,因为如果这样,政府会陷入困境

耶鲁公开课 - 金融市场课程节选