Winnie the Pooh 

Originals a.k.a. Classic 

Milne, A.A. When We Were Very Young. Dutton, 1924

Milne, A.A. Winnie-the-Pooh. Dutton, 1926

Milne, A.A. Now We Are Six. Dutton, 1927

Milne, A.A. The House at Pooh Corner. Dutton, 1928

Milne, A.A. The World of Winnie-the-Pooh: The Complete Winnie-the-Pooh and The House at Pooh Corner. Dutton, 1988.

Milne, A.A. The World of Christopher Robin: The Complete When We Were Very Young and Now We Are Six. Contains When We Were Very Young and Now We Are Six in one volume. Dutton, 1988.

Milne, A.A. The Complete Tales of Winnie-the-Pooh. Contains Winnie the Pooh and The House at Pooh Corner. Penguin USA, 1996.

Milne, A.A. The Complete Poems of Winnie-the-Pooh. Contains Winnie the Pooh and The House at Pooh Corner. Penguin USA, 1996.

Milne, A.A. The Complete Tales and Poems of Winnie-the-Pooh. Contains all four books in one volume. Dutton, 1996.  

The Classic Pooh Treasury

Other

Hoff, Benjamin The Tao of Pooh. Dutton, 1982

Hoff, Benjamin The Te of Piglet. Dutton, 1992

Williams, John Tyerman Pooh and the Philosophers. Dutton, 1995

Allen, Roger E. Winnie-The-Pooh on Management : In Which a Very Important Bear and His Friends Are Introduced to a Very Important Subject Dutton, 1994

Allen, Roger E. and Stephen D. Winnie-The-Pooh on Problem Solving; In Which Pooh, Piglet, and Friends Explore How to Solve Problems, So You Can Too Dutton, 1995