Brown, Floyd D.: 25 Methods for Switching Decks
©1943 Floyd Brown
Softcover, comb-bound, 8.5x11"

©1947 U.F. Grant
Softcover, saddle-stitched, 3.5x6", 18 pages

Reprinted by O'Neal Magic - Revised Edition
Softcover, stapled manuscript, 8.5x11"

25 Methods for
              Switching Decks
U.F. Grant Edition
Image courtesy e-Bay seller SickofChanging
Floyd Brown 25 Methods for Switching Decks
O'Neil Magic Edition
Image courtesy e-Bay seller  CarSkid*5 

Comments:According to Genii's MagicPedia, it was originally published in 1943 as a mimeographed manuscript, and later reprinted by U.F. Grant as No. 2 in a Series of Vest Pocket Books on Magic.

Contents (From U.F. Grant edition book ToC):

1 The Plant Switch
1 The Hat Switch
2 The Black Out Switch
3 The Thurston Switch
4 The Half Deck Switch
5 The Egg Bag Switch
6 The Chinese Switch
6 Brooks' Card Trick
8 A Handkerchief Switch
9 Another Handkerchief Switch
9 The Side Coat Pocket Switch
10 The Paper Switch
11 The Hip Pocket Switch
12 Combination Coat and Vest Switch
12 Rising Card Box Switch
12 Change Bag Switch
13 An Easy Box Switch
13 Another Box Switch
14 Black Art Switch
14 The Card Servante
15 The Vest Pocket Switch
15 Another Vest Pocket Switch
16 Card Tray Switch
16 The Writing Tablet Switch