This booklet is not available in print anywhere that I know of. I have only seen it in pdf form. I have been informed that Kostov has made his book available to everyone for free.
Click this link to download a copy [Click Here]
Kostov - Contents
Sort:
Jul 2, 2018
0
#3
Kostov had a Hippo group here at chess.com several years ago under the name hippochess. I think he also had a Hippo group at Yahoo. When I created my first Hippo group in 2009, I messaged hippochess asking if he wanted to combine forces with both groups under one. He did not reply. 
Jul 18, 2019
0
#4
It should be noted that although this is a book which promotes the idea that 1...b6 is a better way to set-up a Hippo, only five of the eighteen example games were actually started with 1...b6. Kostov has altered the move order of thirteen of these games in order to illustrate his point.
Hippopotamus defence: 1…b6!? approach
Nikolay Kostov - 2009
-------------------------------------------------------
Part I: White’s 1.e4 approach
G01 Kempinski vs McShane
G02 Moroz vs Najer*
G03 Gallagher vs Ponomariov*
G04 Genzling vs Skripchenko*
G05 Toth vs Lima
G06 Wirthensohn vs Hort*
G07 Vescovi vs Lima*
G08 Queralto vs Granados
G09 Maiwald vs Schmaltz
-------------------------------------------------------
Part II: White’s 1.d4/1.c4 approach
G10 Baburin vs Miles
G11 Neverov vs Georgiev
G12 Pelletier vs Onischuk
G13 Brynell vs Spassky
G14 Gyimesi vs Bischoff
G15 Sega vs Lima
G16 Chernin vs Kengis
G17 Baburin vs Bischoff
G18 Loureiro vs Palermo
-------------------------------------------------------
* games which actually started 1...g6 in which Kostov has substituted his 1...b6 method.