Writing Queries That Work by Don McKinney: http://www.writersmarket.com/content/queries_that_work.asp

Sample Query Letter to Pitch an Article to an Academic Journal: http://www.freelancewriting.com/queryletters/01-sample-query-letter-academic-journal.php

How Do I write a Compelling Query Letter?: http://market2editors.com/page8.html
 

THE GREAT AMERICAN QUERY LETTER: http://www.publishersweekly.com/pw/by-topic/columns-and-blogs/soapbox/article/9209-the-great-american-query-letter.html
 

HOW TO STRUCTURE A QUERY LETTER; SAMPLE LETTER: http://paullima.com/blog/2007/03/how-to-structure-a-query-letter-sample-query-letter/