Iconography online : U

  • Milli Tanara Ubertazzi, Natura d’Europa, Novara, Instituto Geografico de Agostini, 2002.
  • Georg UlmerUnsere Wasserinsekten, Leipzig, Quelle & Mener, (1911), 1928.
  • Ernest E. Unwin, Pond problems, The Cambridge nature study series, Cambridge University Press, (1914), 1934, pp. 49-50.
  • Laurence Urdang (dir.)The Random House College Dictionnary revised Edition, New York, 1988.
  • Jim Ure, Bait for trout, being the confessions of an unorthodox angler, Chicago, Henry Regnery compazny, 1973, p. 73.
  • F.A. UrquhartIntroducing the Insect, Ill. E.B.S. Logier, London, Frederick Warne, 1965.
  • Robert Leslie UsingerThe life of rivers and streamsThe World Book Encyclopedia. New York,  MacGraw Hil Book Company, 1967.