Authors and sources
UK copyright on literary works runs for the author's life plus seventy years from the end of the year of death, so the date of death is the practical hinge. Living authors and works plainly still in copyright are out of scope here; cite them by linking to source instead.
Amelia G. M. Murray MacGregor
Amelia Georgiana Murray MacGregor of MacGregor (1841 - 1918). Daughter of Sir John Atholl Bannatyne Murray MacGregor, 3rd Baronet of Lanrick and Balquhidder. She compiled the standard family history of the clan, History of the Clan Gregor, from Public Records and Private Collections (Edinburgh: William Brown, two volumes, 1898 and 1901), which remains the principal printed source for the medieval and proscription-era genealogy.
Her work is out of copyright in the United Kingdom (life + 70 years expired in 1989) and is freely quotable and reproducible.
John MacGregor, W.S.
Author of “Glengyle and its owners”, Glasgow Herald, 3 June 1926. “W.S.” is the post-nominal for Writer to the Signet - a member of the Society of Writers to His Majesty's Signet, the oldest of Scotland's solicitor societies, based at the Signet Library in Edinburgh.
John MacGregor died about 1938, in his eighties. His personal papers passed at his death to the Scottish Records Office, now the National Records of Scotland, where they form part of GD50 - an extensive set including the indexes he compiled across his working life, “huge pages full of all the legal information about every MacGregor he could identify as such, regardless of surname, back as far as legal records go.”
His writings have accordingly been in the public domain in the United Kingdom since the end of 2008 (life plus seventy years from 1938). The 1926 Glasgow Herald article is transcribed in full on its notebook page.