Alexander, G. and Shillito, E. E. 1977. The importance of odour, appearance and voice in maternal recognition of the young in Merino sheep (Ovis aries). Applied Animal Ethology 3: 127–135.
Arnold, G. W. 1966. The special senses in grazing animals.1. Sight anddietary habits in sheep. Australian journal of Agricultural Research 17: 521–529.
Backhaus, D. 1959. Visual acuity in ungulates. Zeitschrift fur Tierpsychologie 16: 454.
Baldwin, B. A. 1979. Operant studies on shape discrimination in goats. Physiology and Behaviour 23: 455–459.
Baldwin, B. A. 1981. Shape discriminationin sheep and calves. Animal Behaviour 29: 830–834.
Barthram, G. T. 1981. Sward structure and the depth of the grazed horizon. Grass and Forage Science 36: 130–131 (abstr.).
Bazely, D. R. 1990. Rules and cues used by sheep foraging in monocultures.In Behavioural mechanisms of food selection (ed. Hughes, R. N.), pp. 343–366. NATO ASI Series vol. G20. Springer-Verlag, Berlin, Heidelberg.
Bazley, D.R.Ensor, C.V. 1989. Discrimination learning in sheep with cues varying in brightness hue. Applied Animal Behaviour Science 23: 293–299.
Carroll, L. 1871. Through the looking glass, what Alice found there. Macmillan, London.
Clarke, P. G. H., Donaldson, I. M. L.Whitteridge, D. 1976. Binocular visual mechanisms in cortical areas I II of the sheep. journal of Physiology (London) 256: 509–526.
Clarke, P. G. H.Whitteridge, D. 1976. The cortical visual areas of the sheep. Journal of Physiology (London) 256: 497–508.
Coile, D. C. and O'Keefe, L. P. 1988. Schematic eyes for domestic animals.Ophthalmic Physiological Optics 8: 215–220.
Entsu, S., Dohi, H.Yamada, A. 1992. Visual acuity of cattle determined by the method of discrimination learning. Applied Animal Behaviour Science 34: 1–10.
Evans, C. R.Piggins, D. J. 1963. A comparison of the behaviour of geometrical shapes when viewed under conditions of steady fixation, and with apparatus for producing a stabilised retinal image. British journal of Physiological Optics 20: 261–274.
Geist, V. 1971. Mountain sheep:a study in behaviour and evolution. University of Chicago Press, Chicago.
Glickstein, M.Millodot, M. 1970. Retinoscopy eye size. Science 168: 605–606.
Hughes, A. 1977. The topography of vision in mammals of contrasting life style: comparative optics retinal organisation. In Handbook of sensory physiology, vol. VII, 5. The visual system in vertebrates (ed. Crescitelli, F.). Springer-Verlag, Berlin.
Hughes, A.Whitteridge, D. 1973. The receptive fields to pographical organisation of goat retinal ganglion cells. Vision Research 13: 1101–1114.
Kendrick, K. 1990. Through a sheep's eye. New Scientist 12May (no. 1716): 62–65.
Kendrick, K. M. 1994. Neurobiological correlates of visual olfactory recognition in sheep. Behavioural Processes 33: 89–111.
Kendrick, K. M.Baldwin, B. A. 1986. The activity of neurones in the lateral hypothalamus zona incerta of the sheep responding to the sight or approach of food is modified by learning satiety reflects food preference. Brain Research 375: 320–328.
Kendrick, K. M.Baldwin, B. A. 1987. Cells in temporal cortex of conscious sheep can respond preferentially to the sight of faces. Science 236: 448–450.
Kendrick, K. M.Baldwin, B. A. 1989. The effects o: sodium appetite on the responses of cells in the zona incerte to the sight or ingestion of food, salt water in sheep Brain Research 429: 211–218.
Knowles, A.Dartnell, H. J. A. 1977. Habitat, habit and visual pigments. In The eye, vol. 2B, The photobiology ofvision (ed. Davson, H.), pp. 581–648. Academic Press, New York.
Lythgoe, J. N. 1979. The ecology of vision. Clarendon Press Oxford.
Muntz, W. R. A. 1974. Comparative aspects in behavioural studies of vertebrate vision. In The eye, vol. 6, Comparative physiology (ed. Davson, H. and Graham, L. T.), pp. 155–226Academic Press, New York.
Newton, I. 1680 in Brewster, D. 1860. Memoirs of the life, writings discoveries of Sir Isaac Newton. Edmonton Douglas, Edinburgh.
Phillips, C. J. C. and Weiguo, L. 1991. Brightness discrimination abilitiesof calves relative to those of humans. Applied Animal Behaviour Science 31: 25–33.
Piggins, D. 1992. Visual perception. In Farm animals the environment (ed. Phillips, C.J.C. and Piggins, D.), pp 131–158. CAB International, Wallingford.
Piggins, D., Muntz, W. R. A.Best, R. C. 1983. The eye of the Amazonian manatee, Trichechus inunguis: oculai refraction gross ocular anatomy, retinal histology photopigment. Marine Behavioural Physiology 9: 111–130.
Piggins, D.Phillips, C. J. C. 1996. Sheep vision in “Through the looking glass what Alice found there”. jabberwocky. In press.
Primrose, J. 1964. The functional anomalies of the eye. In Modern ophthalmology. Volume 3.Topical aspects (ed. Sorsby, A.), pp. 37–42. Butterworths, London.
Sorsby, A., Benjamin, B., Davey, J. B., Sheridon, M.Tanner, J. M. 1957. Emmetropia its aberrations. Special Report Series No. 293. Medical Research Council, UK.
Van Soest, P. J. 1982. Nutritional ecology of the ruminant. O B Books Inc., Oregon.
Walk, R. D. and Gibson, E. J. 1961. A comparative and analytic study of visual depth perception. Psychological Monographs 75: 1–44.
Walls, G. L. 1942. The vertebrate eye its adaptive radiation. Hafner Publishing Company, New York.