I need good introductory texts/publications on brain networks and functional integration/segregation
A good introductory book is "Networks of the Brain" by Olaf Sporns. It will give you a general overview of the ideas and theories in the field. For more details consult the bibliography or read some of the journal articles by Dr. Sporns.

https://mitpress.mit.edu/books/networks-brain

http://www.indiana.edu/~cortex/index.html