Expert Opinion - Query 4

I want to learn different protocols please share some website. 

http://embeddeddesignblog.blogspot.in/search?q=I2C
http://www.embedded.com/design/connectivity/4023975/Serial-Protocols-Compared
http://www.byteparadigm.com/applications/introduction-to-i2c-and-spi-protocols/
https://www.ece.cmu.edu/~ece649/lectures/13_protocols.pdf