historiography
Concise Oxford English Dictionary © 2008 Oxford University Press:
historiography /hɪˌstɔːrɪˈɒgrəfi, -ˌstɒrɪ-/
▶noun the study of the writing of history and of written histories.
■ the writing of history.
– derivatives
historiographer noun,
historiographic adjective,
historiographical adjective.
historiographer noun,
historiographic adjective,
historiographical adjective.
– origin C16: via med. L. from Gk historiographia, from historia ‘history’ + -graphia ‘writing’.
'historiography' also found in these Oxford entries:

