A source that I have found that lists Wilson's Creek on the battle list of Watie's Regiment is Stewart Sifakis': Compendium of the Confederate Armies: Kentucky, Maryland, Missouri, the Confederate Units and the Indian Units. Page 194-95 has the 2nd Cherokee Mounted Rifles with the list of battle honors being on p. 195. This source doesn't show a direct footnote/end note, but the bibliography lists numerous secondary and primary resources for the entire book including the ORs. The exact percentage involved may not be known since other units with partial participation list the number of companies involved.