Articles:
EBSCOhost Subject Search: same-sex marriage OR (gay rights AND marriage) - 2900+ full text articles
ProQuest Subject Search: Login to Proquest to construct this search: (same sex marriage) OR (gay* and marriage) - over 6900 full text articles
"States Debate Marriage Rights (Research Feature)." June 2009. Facts On File World News Digest - issue summary with links to key news events and other features.
Gay Marriage Showdowns: Will voters bar marriage for same-sex couples? CQ Researcher 29 May 2012.
Books:
Catalog - search su:Same-sex marriage or su:gay couples or gay marriage
Ebrary
Sullivan, Andrew. Same-Sex Marriage : Pro and Con. Knopf: 2004.
Alderson, Kevin and Kathleen Lahey. Same-Sex Marriage : The Personal and the Political. Insomniac Press : 2004
Reference Article:
"Defense of Marriage Acts." National Survey of State Laws. Ed. Richard Leiter. 6th ed. Detroit: Gale, 2008.
Web:
State By State: The Legal Battle Over Gay Marriage. NPR.org. 16 Apr. 2009.