Material
Good reference links
Youtube Play Lsit: Internet of Things Video Lectures (NPTEL Lecture Series of Prof. Sudip, IITKGP)
Online Course: Free online course (Audit) (Coursera course on of Things and Embedded Systems)
Website: RFC CoAP
List of books
Internet of Things: A Hands-on Approach Book by Arshdeep Bahga and Vijay K. Madisetti