The Roman Index and its Late Proceedings: A Second Letter to the most Reverend Archbishop Manning

Six Years In Biscay: Comprising A Personal Narrative Of The Sieges Of Bilbao, In June 1835, And October To December, 1836 (1838)

Six Sermons On The Study Of The Holy Scriptures: Their Nature, Interpretation, And Some Of Their Most Important Doctrines, To Which Are Annexed Two Dissertations (1830)

Six Sermons On The Inquiry Is There Immortality In Sin And Suffering? Also, A Sermon On Christ The Life-Giver Or The Faith Of The Gospel (1856)

Six Selections From Irving's Sketchbook: With Notes, Questions, Etc. (1878)

Six Months Among Indians, Wolves and Other Wild Animals in the Forests of Allegan County, Michigan, in the Winter of 1839 and 1840

Six Madrigals To Six Voices (1892)

Six Madrigals To Four Voices (1891)

Six Lectures To Working Men On Christianity (1850)