I haven't read it in a while, but I remember thinking that "Kids are Worth It!" by Barbara Coloroso seemed pretty compatible with Montessori. I personally found the Jellyfish/Brickwall/Backbone (permissive, authoritarian, authoritative) a little overly preachy and obvious but there is a lot of stuff along the lines of children taking responsiblity for their own mistakes, making amends, helping them develop their own judgement, etc. which I think is very much in line with Montessori.
Not a book, but in case you haven't come across it, I found this blog post about the Montessori approach to discipline very informative:
http://montessorihomes.blogspot.se/2011/04/discipline-montessori-perspective.html
Cheers,
Caitlinn
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