(1) Peter Kent 1988 Fortifications of East Anglia
Page(s)157-60
(2) by H M Colvin ... [et al] 1982 The history of the King's Works, volume 4 : 1485-1660 (Part 2)
Page(s)371,389
Further information about monuments may be obtained by contacting NMR Enquiry and Research Services , through the English Heritage website.