How to assess and sell an autographed ball?

Among my late father's belongings, I have found what appears to be a ball autographed by 20 of the 1938 Washington Senators. He did live in DC in the 30's, and would have been 12 at the time. It is not a "baseball" but a "playground ball" like a softball.
How do I figure out if this is "genuine?" How might I estimate its value, and then sell it? My mother is out of money and needs cash, so we want to get the most we can. I would like someone to buy it and be happy with the deal, but not because they grossly underpaid.
Also, are old baseball magazines and stat books of any value? We was apparently quite a fan of baseball as a young man. Oddly, our family were not big baseball fans when I was as kid - just some games on TV, almost never went to ballparks.
I appreciate any advice I can get before venturing out into the world of baseball collectibles.
Here is one not-very-good image of one section of signatures, with Goose Goslin in the center:
How do I figure out if this is "genuine?" How might I estimate its value, and then sell it? My mother is out of money and needs cash, so we want to get the most we can. I would like someone to buy it and be happy with the deal, but not because they grossly underpaid.
Also, are old baseball magazines and stat books of any value? We was apparently quite a fan of baseball as a young man. Oddly, our family were not big baseball fans when I was as kid - just some games on TV, almost never went to ballparks.
I appreciate any advice I can get before venturing out into the world of baseball collectibles.
Here is one not-very-good image of one section of signatures, with Goose Goslin in the center:

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2011 sale Legendary Auctions
http://www.legendaryauctions.com/LotDetail.aspx?lotid=119696
2006 sale Hunt Auctions (multi-ball lot)
http://www.huntauctions.com/online/view_lots_items_list_closed.cfm?auction=28&start_number=101&last_number=200
<< <i>Are you sure that's not a facsimile ball? >>
no, it's hand signed
"Playground" ball hurts the value a bit, lack of authentication could also scare some bidders off. Make sure you have several pics if you list it. Something like this that doesn't come up often might just go quickly for a nice dollar amount.
Are Al Simmons and Rick Farrell anywhere on there? Both HOFers
Good luck with whatever you decide!
Joe
PS Welcome to the boards
If I went the ebay route, would it be reasonable to start at $300 and see what happens? Is it worth having someone do a formal appraisal, or is that just a waste of money?
I do have other photos, and I will take new ones with better lighting - these were just to have something for discussion's sake. I don't have any formal authentication, but the ball is with stuff from my father's childhood, with baseball ephemera from the same period - just sitting in a box under the house. I feel confident it is authentic in terms of being from 1938. But of course, I cannot say of the signatures are all signed by the actual people. Bucky Harris and Nick Altock also signed, and they are manager and coach - it seems to me that if someone were going to fake signatures, they would not bother with staff, but put on more team member names. I wonder if the team visited city playgrounds or scouting events and my dad was there. Here is a list of the 20 signatures:
"Bucky" Harris (signed with the quotation marks)
Jimmy Wasdell
Buddy Myer
J. DeShong
Tony Giuliani
Joe Krakauskas
Chief Hogsett
Goose Goslin
Harry Kelly
Dutch Leonard
Nick Altrock
Peter Appleton
Rick Ferrell
Monte Weaver
Zeke Bonura
Buddy Lewis
Cecil Travis
George Case
Ken Chase
Al Simmons