(1) It's Potty Time (Boy)
WOW Promotional Price: $8.50 (Retail Price $14)
(2) It's Potty Time (Girl)
WOW Promotional Price: $8.50 (Retail Price $14)
Update: New version (Jul 2011) of It's Potty Time (Boy / Girl) is available:
http://worldofwondersbooks.blogspot.sg/2013/01/its-potty-time-boy-girl-2-titles.html
(3) Potty Time with Elmo
WOW Promotional Price: $11 (Retail Price $18)
(4) Dora's Potty Book
WOW Promotional Price: $11 (Retail Price $18)