This Day in Unitarian Universalist History, by Frank Shulman (Boston: Skinner House, 2004) is packed with UU history. Another classic in UU history is Unitarian Universalism: A Narrative History, by David E. Bumbaugh (Chicago: Meadville Lombard Press, 2001).
Frances Watkins Harper
Many of Harper's work are available. For starters, read the Collected Works of Frances Ellen Watkins Harper (Charleston: BiblioBazaar, 2007) or see what your library may hold. There are also a few biographies of Harper. One is Discarded Legacy: Politics and Poetics in the Life of Frances E.W. Harper, 1825-1911 (Detroit: Wayne State University Press, 1994)
Read more about Maslow's theory of human motivation at Classics in the History of Psychology.