"The Truth about Terra" is a book (with a golden ginkgo leaf in it) poor mad Aqua gave her twin sister Marina before going back to her Home (Ada, 1.1: Marina's herbarium).

The Truth about Pyecraft is a story (1903) by H. G. Wells, the author of The War of the Worlds (1898). Cf. "A small map of the British Commonwealth - say, from Scoto-Scandinavia to the Riviera, Altar and Palermontovia - as well as most of the U. S. A., from Estoty and Canady to Argentina, might be quite thickly prickled with enameled red-cross-flag pins, marking in her War of the Worlds, Aqua's bivouacs." (Ada, 1.3)

Gottfried Plattner, the hero of H. G. Wells' The Plattner Story (1896), managed to visit the Other World where he spent nine days (and saw, among other dead, his late mother). Plattner reminds one of Rattner, Van's older colleague at Kingston University, the author of a (difficult and depressing) book on Terra ("The Truth about Terra"?):

'Rattner on Terra!' ejaculated Lucette. 'Van is reading Rattner on Terra. Pet must never, never disturb* him and me when we are reading Rattner!' (Ada, 2.5)

Rattner's nephew Bernard and his friends visit Van at Voltemand Hall where they "get dreadfully drunk" on Van's cognac and then drain a gallon of Gallows Ale (2.6). Rattner + Ai (the champagne Van, Ada and Lucette drink a week later at Ursus: 2.8) = Antiterra (aka Demonia, Terra's twin planet on which Ada is set).

Fat Pyecraft, the hero of the Wells story, loses his weight dramatically and has to wear lead underclothing in order to walk like other men do and not fly away (although still fat, he weighs practically nothing and gravitation lost its hold of him**). The narrator compares Pyecraft to "clouds in clothing."

Now, "Облако в штанах" ("The Trousered Clowd," 1916) is an autobiographical poem by VN's late namesake, V. V. Mayakovsky. Mayakovsky is the author of "Vladimir Mayakovsky. A Tragedy" (1913) and "Vladimir Iliych Lenin" (a kind of futurist ode, 1925). In 1920 Wells visited Soviet Russia, met Lenin and wrote Russia in the Shadows calling Lenin "the Kremlin Dreamer."

*'You will "sturb," Van, with an alliteration on your lips,' jested old Rattner, resident pessimist of genius, for whom life was only a 'disturbance' in the rattnerterological order of things - from 'nertoros,' not 'terra' (2.5).

**Van, too, manages to overcome gravity in his Mascodagama stunt (1.30). The Ranter (he + Rattner) is the usually so sarcastic and captious Chose weekly that praised, in an unsigned editorial, Mascodagama's performance at the Rantariver Club. Ranta + Garshin = Granta + Arshin (Ranta - Antiterran name of Granta; Garshin - V. M. Garshin, 1855-88, the author of "The Red Flower," 1883, who committed suicide by jumping from the fifth floor of his apartment building; Granta - the Cam river; Arshin - Van's patient at Kingston, an acrophobe: 2.6; arshin - Russian measure, equivalent to 28 inches)