At some time I think it’s a good ideas to save a list of good-reads.

http://www.datasciencecentral.com/profiles/blogs/the-big-data-analytical-problems-inflexible-data-structure/

https://www.topcoder.com/community/data-science/data-science-tutorials/

https://www.analyticsvidhya.com/blog/2015/06/regular-expression-python/

http://wesmckinney.com/blog/groupby-fu-improvements-in-grouping-and-aggregating-data-in-pandas/

https://www.analyticsvidhya.com/blog/2014/11/text-data-cleaning-steps-python/