Below is a list of websites, books and academic articles focusing on henge monuments. It is by no means exhaustive, but is representative of the field.
www.pastscape.org.uk (searchable database)
http://canmore.rcahms.gov.uk/en/site/26006/details/north+mains+strathallan/ (just one example of henge record)
Bender, B. (1998) Stonehenge: Making Space. Oxford: Berg.
Bradley, R. (2011), Stages and Screens. Edinburgh: Society of Antiquaries of Scotland.
Cleal, R., Walker, K. and Montague, R. (1995) Stonehenge in its Landscape: Twentieth Century Excavations. London: English Heritage.
Gibson, A.M. (2000) Stonehenge and Timber Circles. Stroud: Tempus.
Harding, J. (2003) Henge Monuments of the British Isles. Stroud: Tempus.
Pitts, M. (2001) Hengeworld (2nd Ed). London: Arrow.
Richards, J. (1990) The Stonehenge Environs Project. London: English Heritage.
Wainwright, G.J. (1990) The Henge Monuments. London: Thames and Hudson.
Barclay, G.J. (1989) Henge monuments: reappraisal or reductionism? Proceedings of the Prehistoric Society 55, 260-3.
Barclay, G.J. (1999) Cairnpapple revisited: 1948-1998. Proceedings of the Prehistoric Society 65, 17-46.
Barclay, G.J. and Russell-White, C.J. (1993) Excavations in the ceremonial complex of the fourth to second millennium BC at Balfarg/Balbirnie, Glenrothes, Fife. Proceedings of the Society of Antiquaries of Scotland 123, 43-210.
Burl, H.A.W. (1969) Henges: internal structures and regional groups. Archaeological Journal 126, 1-28.
Carver, E. (2011) Stonehenge World Heritage Site – A Strategy For Interpretation, Learning and Participation 2010-2015. (Available as a pdf download form http://www.english-heritage.org.uk/publications/stonehenge-whs-interpretation-learning-participation-strategy/)
Clare, T. (1987) Towards a reappraisal of henge monuments: origins, evolution and hierarchies. Proceedings of the Prehistoric Society 53, 457-78.
English Heritage (2001) Archaeological Research Agenda for Avebury WHS. (Available as pdf download from (http://www.english-heritage.org.uk/publications/archaeological-research-agenda-avebury)
Gibson, A. (1998) Hindwell and the Neolithic palisaded sites of Britain and Ireland. In: A. Gibson and D. Simpson (eds.) Prehistoric Ritual and Religion, pp68-79. London: Sutton.
Gibson, A. (2010) Excavation and survey at Dyffryn Lane henge complex, Powys, and a reconsideration of the dating of henges. Proceedings of the Prehistoric Society 76, 213-48.
Harding, J. (2000) Later Neolithic ceremonial centres, ritual and pilgrimage: the monument complex of Thornborough, North Yorkshire. In: A. Ritchie (ed.) Neolithic Orkney in its European Context, 31-46. Cambridge: McDonald Insitute.
Harding J. (2012). Henges, rivers and exchange in Neolithic Yorkshire. In: Jones, A., Pollard, J., Allen, M., Gardiner, J, ed. Image, Memory and Monumentality: Archaeological Engagements with the Material World (a Celebration of the Academic Achievements of Professor Richard Bradley). Oxford and Oakville: Oxbow Books and Prehistoric Society, pp. 43-51.
Richards, C.C. (1996) Henges and water: towards an elemental understanding of monumentality and landscape in late Neolithic Britain. Journal of Material Culture 1, 313-36.
Speak, S. and Burgess, C. (1999) Meldon Bridge: a centre of the third millennium BC in Peeblesshire. Proceedings of the Society of Antiquaries of Scotland 129. 1-118.
Thomas, J.S. (2004) The later Neolithic architectural repertoire: the case of the Dunragit complex. In: R. Cleal and J. Pollard (eds.) Monuments and Material Culture: Papers on Neolithic and Bronze Age Britain in Honour of Isobel Smith, pp98-108. East Knoyle: Hobnob Press.
Thomas, J.S. (2010) The return of the Rinyo-Clacton Folk? The cultural significance of the Grooved Ware Complex in Later Neolithic Britain. Cambridge Archaeological Journal 20.
Wainwright, G.J. (1969) A review of henge monuments in the light of recent research. Proceedings of the Prehistoric Society 35, 112-133.