Wikipedia keeps its page on same-sex marriage updated with background, links, state-by-state information and charts. Wikipedia also has a page about Christian churches around the world that have approved same-sex marriages. As with any open-source website, information on Wikipedia should be confirmed before it’s used.

The Williams Institute focuses on sexual-orientation law and public policy, and its website has a number of resources on same-sex marriage. Scholars from the think tank, which is based at California’s UCLA law school, participated in friend-of-the-court briefs in both March 2013 cases before they went the Supreme Court.

Rutgers’ law library posts a bibliography of legal literature on the topic.

The National Marriage Project at the University of Virginia conducts research and analysis on marriage issues. Brad Wilcox is director.

NPR has posted a timeline of significant developments in the debate from 1972 through 2012.

The National Conference of State Legislatures maintains a page on state laws defining marriage.

Rabbi Toba Spitzer is president of the Reconstructionist Rabbinical Association, the first openly gay woman to become its leader. She is the head rabbi at Congregation Dorshei Tzedek in West Newton, Mass.

Rabbi Sharon Kleinbaum is a Reform rabbi who leads Congregation Beth Simchat Torah in New York City, the world’s largest synagogue for gay, lesbian, bisexual and transgender Jews.

Read this July 15, 2009, Chicago Tribune article about the Episcopal Church, the American arm of the Anglican Communion, voting to make gays and lesbians eligible for any ordained ministry.