Question: Little Nellie 007 is a book by an English military historian and author, who specializes in what?
Context: Willem Jan Knoop (Deventer, May 2, 1811 – The Hague, January 24, 1894) was a Dutch lieutenant-general, military historian, and politician.  As a young captain of the Dutch General Staff he wrote a rebuttal of the English military historian captain William Siborne's account of the Battle of Quatre Bras and the Battle of Waterloo, published as "History of the war in France and Flanders in 1815" in 1844, in which Siborne disparaged the conduct of the Dutch army at these battles.  Siborne's book had caused a furore in the Netherlands as he saw fit to insult the honor of the Dutch army, and of king William II of the Netherlands, who as Prince of Orange had commanded that army at both battles, and was revered as a national hero by the Dutch.  As Siborne's book is still in use as a source for Anglophone historiography of the battles, and is still the subject of controversy, Knoop's criticisms are still relevant, and play a role in this controversy. Little Nellie 007 (ISBN  ) (1991) is a book by Bruce Barrymore Halpenny about the James Bond autogyro, "Little Nellie" as featured in the film "You Only Live Twice" and her "father", Wing Commander Retd.  Ken Wallis. Ramsay Weston Phipps (10 April 1838 – 24 June 1923) was an Irish-born military historian and officer in Queen Victoria's Royal Artillery.  The son of Pownoll Phipps, an officer of the British East India Company's army, he was descended from the early settlers of the West Indies; many generations had served in the British, and the English military.  Phipps served in the Crimean War, had a stint of duty at Malta, and helped to repress the Fenian uprising in Canada in 1866. The Face of Battle is a 1976 non-fiction book on military history by the English military historian John Keegan.  It deals first with the structure of historical writing about battles, the strengths and weaknesses of the "battle piece," and then with the structure of warfare in three time periods—medieval Europe, the Napoleonic Era, and World War I—by analyzing three battles: Agincourt, Waterloo, and the Somme, all of which involved English soldiers and occurred in approximately the same geographical area. Bruce Barrymore Halpenny (born 1937 in Caistor, Lincolnshire) is an English military historian and author, specialising in airfields and aircraft, as well as ghost stories and mysteries.  He is also a broadcaster and games inventor. Michael John William Chappell BEM (born 14 September 1934), better known as Mike Chappell, is an English military historian and illustrator of military books. Correlli Douglas Barnett CBE FRHistS FRSL FRSA (born 28 June 1927) is an English military historian, who has also written works of economic history, particularly on the United Kingdom's post-war "industrial decline". Andrew Robertshaw was born in Sheffield, England, and is an English military historian, curator, author and educator.  He is best known for his television appearances, in programmes such as "Two Men in a Trench" and "Time Team".  He was a military advisor on the film "War Horse". Wet Nellie is a custom-built submarine, created for the 1977 James Bond film "The Spy Who Loved Me" in the shape of a Lotus Esprit S1 sports car.  The Esprit was chosen to give James Bond a glamorous car to drive.  "Wet Nellie" is named in reference to Little Nellie, an autogyro featured in the James Bond film "You Only Live Twice".  Little Nellie was named after Nellie Wallace. Sir Antony James Beevor, {'1': ", '2': ", '3': ", '4': "} (born 14 December 1946) is an English military historian.  He has published several popular histories on the Second World War and the 20th century in general.
Answer: airfields and aircraft