Christian (8.) Frederik’s diary dated 26.11.1840 (“was shown C 4 statue cast [in plaster]”).
Letter dated 1.9.1841 from C.F. Wilckens to Thorvaldsen (“King Christian 4 statue cast in metal”).
Letter dated 23.12.1841 from Christian (8.) Frederik to Thorvaldsen (“The casting of C IV statue is very successful”).
Letter dated 14.1.1842 from Just Mathias Thiele to Thorvaldsen (“Chr 4.’s statue has been cast, and the chasing is progressing rapidly”).
Letter dated 15.2.1842 from Thorvaldsen to Christian (8.) Frederik (“I have been very pleased to hear that the casting of Christian 4.s statue is so successful.
Other references
Rigmor Stampe (ed.): Baronesse Stampes Erindringer om Thorvaldsen, Copenhagen 1912, p. 62-63, 65.