The Anglo-Saxon Chronicle has passing references to the earlier relationship between William and Edward the Confessor: version "C" calls William Edward's "kinsman" (we know they were in fact first cousins twice removed, duke Richard I being their common ancestor). "The Gesta Normannorum Ducum" was first composed by William of Jumieges, a contemporary of William the Conqueror, and based on the earlier work of Dudo of St Quentin, whose writings date between c. 996 and 1015: William of Jumieges began his writing in the 1050's.

(In the "Gesta" we learn of an earlier attempt by William the Conqueror's father to provide armed aid for his cousins, the exiled athelings Edward and Edgar: the fleet was grounded on the Isle of Jersey by bad weather until it had to disband back to the mainland: so we know that in the 1030's Norman help for the legitimate heirs of the English crown was forthcoming.)

"About fourteen manuscripts of Dudo's work survive today, and we have forty-seven manuscripts of the GND in one or other of its various redactions." (Elisabeth M. C. Van Houts, Clarendon Press, Oxford Press 1992).

The "Vita Edwardi" (trans Barlow) was completed between 1065 and 1067, at the assumed behest of queen Edith. The "Encomium Emmae reginae" by Alistair Campbell is perhaps available: but the "Vita Edwardi" is perhaps impossible to find a copy of (for sale). The former is a work commissioned by queen Emma herself.

Those are about the only original sources with pre-conquest roots that I know of which have content about English and Norman relations.

But now I see that you said "secondary sources": secondary sources are numerous: Orderic Vitalis(Jumieges/Torigni), William of Malmesbury, Henry of Huntingdon, Florence of Worcester, are the main secondary Anglo-Norman sources.

If by "secondary sources" you actually meant "seminal works" then the list is formidably long. Among the most useful (for me) for describing English-Norman relations have been David C. Douglas' William the Conqueror, David Howarth's 1066 The Year of the Conquest and Jim Bradbury's The Battle of Hastings.

But I prefer to go to translations of the original sources myself. (Speaking of which: if anyone knows how I can obtain a copy of the "Vita Edwardi" by Barlow, I would appreciate it :))