Behslich, Dean

Dean Behslich is listed by Asbury as one of his sources of information for the Barbary Coast. At this time I have not found any further information about him.

Older, Fremont

The legendary San Francisco journalist and newspaper editor Fremont Older was one of those thanked by Asbury as one of the sources of information for the Barbary Coast.

https://en.wikipedia.org/wiki/Fremont_Older

Gleeson, Edward T.

Edward T. Gleeson, an editor of the San Francisco Call, was one of the sources thanked by Asbury in his introductory Author's Note.

Jones, Idwal

Idwal Jones is one of those listed in thanks by Asbury at the beginning of the book. Jones was a novelist who wrote historical fiction set during the Gold Rush, as well as a history of the Montgomery Block.

https://en.wikipedia.org/wiki/Idwal_Jones_(novelist)

Asbury, Herbert

Herbert Asbury (Image from the Daily Journal Online)

As numerous sources will tell you, the journalist Herbert Asbury, author of The Barbary Coast, was more attuned to a colorful story than to historical accuracy. Thus, a major focus of this Annotated Barbary Coast (ABC) will be to tease out, whenever possible, just what in his book can reasonably be believed to be accurate, what can not, and where between these two poles the rest lies.

More details of his life and writings can be found online:

https://en.wikipedia.org/wiki/Herbert_Asbury

I am not (yet) aware of any sustained investigation into Asbury's life. A good many writers, mostly commenting on his Gangs of New York, hold him at arm's length--noting his inaccuracies and errors, while still relying on him when convenient.