Sherry Irvine's most informative article, Protestant Nonconformity in Scotland - An Introduction [Part One] [Part Two], which first appeared in Rootsweb Review Vol 4, No 17 (23 April 1999) and Vol 4, No 27 (30th June 1999).
A bibliographic guide is Malcolm B. MacGregor's Sources and Literature of Scottish Church History, published by McCallum in 1934. A more recent work which may also be of help is J.H.S. Burleigh's A Church History of Scotland, published by OUP in 1960.
See History of the Scottish Church by Rev. Edwin Lee.
The Free Church and the Leaders of the Disruption of 1843. (This third breakaway was the 'Disruption' associated with Thomas Chalmers and led to the formation of the Free Church. While the Seceders and Relief came about by the separation of one or two at a time the 'Disruption' saw over 400 hundred ministers resign from the Church of Scotland)
Oliver and Boyd's New Edinburgh Almanac and National Repository was published from 1837. With local supplements, it covered much of Scotland, and had detailed information on the churches and their denominations. The 1853 edition is available for search online in Ancestry (with details available to subscribers). Post Office Directories are also useful in providing details of churches.
Churches to Visit in Scotland by John R Hume, guide showing opening times and what to see for 900 churches from Scotland's Churches Scheme.
For information on ministers and/or congregations, the following reference works may be of help:
Fasti Ecclesiae Scoticanae ("the succession of Ministers in the Church of Scotland from the Reformation") by Hew Scott, new edition published at Edinburgh from 1915 to 1928 (7 volumes) with four more recent volumes taking the coverage up to 1999. Volumes I and II are provided online by David Walker in his Scottish Ministers pages.
History of the Congregations of the United Presbyterian Church from 1733 to 1900 by Rev. Robert Small, published in 2 volumes in 1904 at Edinburgh
Annals of the Free Church of Scotland edited by Rev. William Ewing, published in 2 volumes in 1914 at Edinburgh
The Fasti of the United Free Church of Scotland 1900-1929 edited by John Lamb, published at Edinburgh in 1956
The Reformed Presbyterian Church in Scotland, its congregations, ministers and students by William J. Couper, published at Edinburgh in 1925
History of the Scottish Episcopal Church from the Revolution to the Present Time by John P. Lawson, published at Edinburgh in 1843
A Short History of the Episcopal Church in Scotland from the Restoration to the Present Time by Frederick Goldie, published in 1952
The Scottish Congregational Ministry 1794-1993 by Rev. Dr. William D. McNaughton, published in 1993 at Glasgow by the Congregational Union of Scotland
A History of Scottish Congregationalism by Harry Escott, published in 1960
Scottish Episcopal clergy 1689-2000 edited by David M. Bertie, publish at Edinburgh in 2000. ISBN 0-567-08746-8
Dictionary of Scottish Church history and theology edited by Nigel M. de S. Cameron [et al.], published at Edinburgh in 1993. ISBN 0-567-09650-5