If you include source: in your query, Google News will restrict your search to articles from the news source with the ID you specify. For example, [ election source:times_of_india ] will return articles with the word "election" that appear in ther Times of india.
To find a news source ID, enter a query that includes a term and the name of the publication you're seeking. You can also specify the publication name in the "news source" field in the Advanced News Search form. You'll find the news source ID in the query box, following the source: search operator. For example, let's say you enter the publication name Ha'aretz in the News Source box, then you click the Google Search button. The results page appears, and its search box contains [ peace source:ha_aretz__subscription_ ]. This means that the news source ID is ha_aretz__subscription_. This query will only return articles that include the word "peace" from the Israeli newspaper Ha'aretz.