A four-page handwritten letter in pencil, presumably unsent, from Barlow to Robert E. Howard’s father, expressing his condolences on the author’s “shocking death”. 

This letter can be found on page 71 in The Collected Letters of Doctor Isaac M. Howard.

Page 1 of Barlow's letter to Robert E. Howard's father, expressing his condolences on the author's "shocking death"

Page 2 of Barlow's letter to Robert E. Howard's father, expressing his condolences on the author's "shocking death"

Page 3 of Barlow's letter to Robert E. Howard's father, expressing his condolences on the author's "shocking death"

Page 4 of Barlow's letter to Robert E. Howard's father, expressing his condolences on the author's "shocking death"

Source:
Heritage Auctions website.