languages with SOV word order with case-marking vs. languages with SVO word order without case-marking

[Ted Gibson]

Dear Funknet people:

Can you please provide me with references for the claim that word order in language tends to shift between SOV word order with case-marking to SVO word order without case-marking?  Or any similar such claim?  I am citing Givon for this claim, but I have heard from others that there are some claims that pre-date him.  I am interested in all such references: both pre- and post-Givon.

Yours sincerely,

Ted Gibson