Please answer a question about the following article about Political corruption:

Snyder and Strömberg found "that a poor fit between newspaper markets and political districts reduces press coverage of politics. ... Congressmen who are less covered by the local press work less for their constituencies: they are less likely to stand witness before congressional hearings ... . Federal spending is lower in areas where there is less press coverage of the local members of congress." Schulhofer-Wohl and Garrido found that the year after the Cincinnati Post closed in 2007, "fewer candidates ran for municipal office in the Kentucky suburbs most reliant on the Post, incumbents became more likely to win reelection, and voter turnout and campaign spending fell.

Who discovered the correlation that congressman who have less local press coverage work less for the people who elected them?
Snyder and Strömberg