We've often referred to Teddy Roosevelt's speech to the Knights Of Columbus on Columbus Day, 1915, in which he said "The one absolutely certain way of bringing this nation to ruin, of preventing all possibility of its continuing to be a nation at all, would be to permit it to become a tangle of squabbling nationalities..."
However, it's hard to find copies of the original speech online. In pursuit of VDARE.com's policy of always searching out original sources, here's the New York Times's report, from October 13, 1915:'Roosevelt Bars the Hyphenated' . The URL is really long, but you can use this version:http://tinyurl.com/trhyph
Link via today's version of Wikipedia. This is how you should use Wikipedia—to find original sources.
Most academics will reference this quote to the version published in Immigration and Americanization; selected readings,Compiled and edited by Philip Davis, assisted by Bertha Schwartz ([c1920])