Books:
Cohn - Agile Estimating and Planning
Kniberg - Scrum and XP from the Trenches
  http://www.infoq.com/minibooks/scrum-xp-from-the-trenches

Small:
ScrumTrek - Agile Cheklist

Critique:
http://www.quora.com/Why-do-some-developers-at-strong-companies-like-Google-consider-Agile-development-to-be-nonsense/answer/Michael-O-Church
http://www.e-xecutive.ru/management/practices/1987154-pochemu-agile-ne-prizhivetsya-v-rossii
    (Agile and cultural differencies)