Historical clue formulations

• "Nature" essayist's inits. — 2015-11-11
• Inits. of Thoreau's mentor — 2014-09-12
• "Self-Reliance" essayist's inits. — 2012-03-31
• "Concord Hymn" writer's inits. — 2007-03-11
• Literary monogram — 2003-10-25
• Literary monogram — 2003-05-24
• Literary monogram — 1996-01-12