The Source Library page contains some of the resources I consult on 17th century warfare in the Celtic Fringe of the British Isles (and occasionally elsewhere).
SCOTLAND – 1638 – 1649:
Highland Warrior – Alasdair MacColla and the Civil Wars, David Stevenson (John Donald Publishers, Edinburgh, 1980)
The Campaigns of Montrose, Stuart Reid (The Mercat Press, Edinburgh, 1990)
'Famous By My Sword' The Army of Montrose and the Military Revolution, Charles Singleton (Helion & Company Ltd, Solihull, England, 2014)
The Heather and the Gale – Clan Donald and Clan Campbell during the Wars of Montrose, Ronald Williams (House of Lochar,Isle of Colonsay, Scotland, 1997)
Memoirs Of The Most Renowned James Graham, Marquis of Montrose, George Wishart (circa 1647) (trans and reprint Archibald Constable & Co, Edinburgh, 1819) (Google eBook)
A Short Abridgement of Britane's Distemper, From the Yeare of God MDCXXXIX <1639> To MDCXLIX <1649>, Patrick Gordon of Ruthven (circa 1649 and after) (The Spalding Club, Aberdeen,1844)(Google eBook)
The History of the Troubles and Memorable Transactions in Scotland (Vol II, 1642 – 1645), John Spalding (circa 1645?)(T. Evans, London, 1792)(Google eBook)
Auldearn 1645 The Marquis of Montrose's Scottish Campaign, Stuart Reid (Osprey Publishing, Oxford, 2003) (Kindle Edition)
Montrose, C. V. Wedgewood (orig. pub. 1952, Sutton Publishing Limited, 1998)
The History of the Troubles of Great Britain: Containing a particular Account of the Most Remarkable Passages in Scotland from the Year 1633 to 1650,
Robert Monteth (trans James Ogilvie, 2nd ed, A. Millar, London, 1737)(Google eBook)
IRELAND – 1641 – 1649:
The Laggan Army in Ireland 1640 – 1685, Kevin McKenny (Four Courts Press, Dublin, 2005)
Scottish Covenanters and Irish Confederates Scottish-Irish Relations in the mid-seventeenth Century, David Stevenson (Ulster Historical Foundation, Belfast, 1981)
Ireland From Independence to Occupation 1641 – 1660, Jane Ohlmeyer, ed. (Cambridge University Press, Cambridge, 1995)
Confederate Catholics At War 1641 – 49, Pa'draig Lenihan (Cork University Press, Cork, 2001)
The History of the Warr of Ireland From 1641 To 1653 by A British Officer Of The Regiment of Sir John Clottworthy, Anon. (circa 1675?) ed. and notes. E(lizabeth?). H(ogan?).
(McGlashan & Gill, Dublin, 1873) (Google eBook)
The Battle of Benburb, Clive Hollick (Mercier Press, Cork, 2011)
WEAPONS, TACTICS, and ORGANIZATION
Destructive & Formidable – British Infantry Firepower 1642 – 1765, David Blackmore (Frontline Books, London, 2014)
Pike and Shot Tactics 1590 – 1660, Keith Roberts (Osprey Publishing, Oxford, 2010)
Fighting Techniques Of The Early Modern World AD 1500 ~ 1763 Equipment, Combat Skills, and Tactics, Christer Jorgensen, et.al.(Thomas Dunne Books, St. Martin's Press, 2005)
Celtic Warfare 1595 ~ 1763, James Michael Hill (John Donald Publishers, Edinburgh, 1986)
Warfare In The Seventeenth Century, John Childs (Cassell & Co, London, 2001)
Scots Armies of the 17th Century 3. The Royalist Armies 1639 – 46, Stuart Reid (Partizan Press, Leigh-on-Sea, England, 1989)
A Regimental History of the Covenanting Armies 1639 ~1651, Edward M Furgol (John Donald Publishers, Edinburgh, 1990)
GENERAL HISTORIES of the PERIOD
Civil War The Wars of the Three Kingdoms 1638 – 1660, Trevor Royle (Abacus – Little,Brown, London, 2004)
England Under The Stuarts, George Macaulay Trevelyan (vol. V – A History of England in Eight Volumes [Charles Oman, ed.], Methuen & CO LTD, London, 1904)
The British Wars 1637 – 1651, Peter Gaunt (Routledge, London, 1997)
History Of The Great Civil War 1642 – 1649, Four Vols., Samuel Rawson Gardiner (orig. pub. 1886-1901, The Windrush Press, London, 1987)
The King's War 1641 – 1647, C. V. Wedgwood (orig. pub. 1958, Penquin Books, Harmondsworth, England, 1983)
The Civil Wars In Britain & Ireland 1638 – 1651, Martyn Bennett (Blackwell Publishers Ltd, Oxford, 1997)
The Concise Encyclopedia of the Wars of England, Scotland, and Ireland 1639 – 1660, Stephen C. Manganiello (Scarecrow Press, Inc, Lanham, Maryland, 2004)
MILITARY and other SPECIALIZED HISTORIES of the PERIOD
The Civil Wars A Military History of England Scotland and Ireland 1638 – 1660, John Kenyon and Jane Ohlmeyer, eds.(Oxford University Press, Oxford, 1998)
Going to the Wars The Experience of the British Civil Wars 1638 – 1651, Charles Carlton (Routledge, London,1992)
Dealing in Death The Arms Trade and the British Civil Wars, 1638 – 52, Peter Edwards (Sutton Publishing Limited, Stroud, England, 2000)