The study is described as the first to demonstrate the indirect spread of happiness.

VOA: special.2009.01.21

In the 1920s, things changed because the telephone first became widely spread.

在20世纪20年代,随着电话的普及,情况发生了改变

耶鲁公开课 - 金融市场课程节选

"I believe that most Hong Kong people will feel that we have won the first battle, able to control the spread of infection from the first index patient,"

VOA: standard.2009.05.08