Regarding the story Yellow Cobra.

Kline was not only a popular pulp author, sharing the pages of Weird Tales and other pulps with REH, but he also was an agent for other pulp authors, including REH. This letter discusses REH’s tales “Yellow Cobra,” “Turkish Menace”, “Jade Monkey” and “Cultured Cauliflowers”.

These were all Sailor Steve Costigan stories, though some were later changed to Sailor Dennis Dorgan. Signed by Kline.

Source:

Windy City 2022 Auction Catalog.