Begma is a state of mind, and one which can be contributed to by any number of works of fiction and non-fiction, some of which are listed below. Feel free to add more!
Buchan, John:'The 39 Steps', and the other Richard Hannay novels, whilst a little late show well the espionage between Begma and Prussevania
Childers, Erskine: 'The Riddle of the Sands', a 1903 novel about naval espionage between England and Germany captures the Begma/Prussevanian mood very clearly
Conan-Doyle, Sir Arthur: His 'Professor Challenger' books, especially 'The Lost World' show adventurous Begman Academia well, whilst 'The Adventure of the Naval Treaty' shows early espionage with Sherlock Holmes involved, and would be suitable to some Begman Characters
Gibson, William and Sterling, Bruce: 'The Difference Engine' depicts a computerised Victorian London, based on mechanical computing. Its themes are also applicable to espionage between Begma and Mariannia
Grimm, Jacob and Grimm, Wilhelm: 'Children's and Household Tales', aka 'The Fairy Tales of the Brothers Grimm', in their darker versions conjure up some of the possible events in the darker woods of Ruristania.
Haggard, H Rider: ''King Solomon's Mines' and its sequels and 'She' are adventure stories- Begman heroes exploring the Dark Continent. Allan Quartermain is an example of a Begman adventurer/hunter. Sir Henry Curtis is a Begman Aristocratic adventurer, and Captain Good is a Begman military officer on leave.
Hodgson, William Hope: The 'Carnacki' stories are technically a decade or so post period, but very Begman in feel, comprising the work of a psychic detective (which is a say a detective into supernatural matters), in the pre-World War one world. He makes use of the 'Electric Pentacle' to protect him.
Hope, Anthony: 'The Prisoner of Zenda', and 'Rupert of Hentzau' are the fundamental basis for Ruristania, but other 'Englishman in Central Europe', up to and including 'Dracula' also fit the Ruristanian ideal.
Hugo, Victor:'Les Miserables' shows Mariannian street uprisings.
Moorcock, Michael: The 'Warlord of the Air', 'The Land Leviathan', and 'The Steel Tsar' depict alternate late Victorian/Edwardian worlds with Begman Technology
Moore, Alan and O'Neil, Kevin: 'The League of Extraordinary Gentlemen, volumes 1-2'
Newman, Kim: 'Anno Dracula'- an alternate timeline branching off Dracula, featuring almost all the famous characters of Victorian fiction in cameo roles.
Pullman, Phillip: The 'His Dark Materials' trilogy shows SCIENCE in a Mystical world. And also BALLOONS!
Stoker, Bram: 'Dracula'- Dr Seward and Professor van Helsing in particular are Begman Medical men, whilst Lord Godalming and Harker are examples of more adventurous Begman. Quincy P. Jones is a rare example of a 'Western' type from East Begma in this genre (there are also a few in Holmes stories)
Verne, Jules: Most of his works, especially '20,000 Leagues under the Sea'
Wells, HG:Most of his works, to be honest. He's one of the classics of Early Science Fiction, for example, 'The First Men in the Moon'.
Barton-Wright, EW: Bartitsu. First described in a series of articles, some of which are available online, this is the Begman martial art. An introduction can be found here and one of Barton-Wrights own articles is reprinted - self defence with a walking stick
Chambers, SJ and VanDerMeer, Jeff: The Steampunk Bible
The Adventures of Sherlock Holmes: Those starring Jeremy Brett are probably the best small screen Holmes adaptation
The First Men in the Moon: Professor Cavour simply _is_ a Begman. The 2010 TV movie of HG Well's book is a fine evocation of the style.
The Murdoch Mysteries
The Onedin Line: Rather dated now, but an example of Begman Trade
Penny Dreadful: What happens when an East Begman gunslinger from a travelling show encounters the UnCanny in Begma city? This!
Ripper Street: A more than slightly Begman("I shall apply FORENSICS to this problem!") series.
Upstairs, Downstairs: Either the original or new series show life for upper and lower class Begman.
The Extraordinary Adventures of Adele Blanc-Sec- A movie so Begman it hurts.
For a Few Dollars More- Yes. You read that right. East Begman bounty hunters. But in particular, the moment Lee van Cleef starts messing around with adding things to his guns in order to make a shot which the Man with no Name viewed as impossible.
The Golden Compass- A flawed realisation of the book, but with good visuals
The Importance of Being Ernest- Upper Class Begman Romance!
The Prisoner of Zenda- A Begman travelling in Ruristania, and the adventures he gets into
** The Riddle of the Sands **- The Riddle of the Sands is a 1970's movie version of the 1903 novel of the same name by Erskine Childers, showing Espionage, Adventure and Thrilling Things. Begman Playboy and gentleman sea captain foil Prussevanians, basically.
Sherlock Holmes- the Robert Downey Jr version, with the first one in particular showing how Mystical things have Engineering solutions! Also useful for those who learn FGT-BT
Stardust- This is a 'Begman goes adventuring in Shadow' sort of story/movie.
Van Helsing- Adventures in Ruristania!
Wild Wild West- this somewhat flawed movie shows what life may be like in East Begma
Jeff Wayne : The War of the Worlds. Both the Martian War Machines, and elements of the human life are appropriate to Begma.
Girl Genius: I mean, obviously.
The Thrilling Adventures of Babbage and Lovelace : As illustrated by Sydney Padua, the adventures of Charles Babbage, and Ada, Countess of Lovelace (yes, Lord Byron's daughter), fighting crime in an alternate 19th century where he actually built his Analytical Engine, and she didn't die in her mid 30's of cancer.