Signed by Gregg

Hey everyone! How are you? New here. A few years ago my in-laws gave us four small books on shorthand by Gregg. They are all signed and are as follows:
Gregg Shorthand: New and Revised Edition 1916
Gregg Shorthand Dictionary: New and Revised Edition 1916
Short Classics in Shorthand: "Gregg Writer Edition" 1927
Gregg Shorthand Anniversary Edtion (Advance copy): 1929
They also gave us a couple letters by him: one written, one typed.
Not big into shorthand but was wondering if anyone here may know if there is a market for this type of thing.
Any info. would be most appreciated. Thanks

(by stevew101 for everyone)