references added for background
references added for background

raazesh-sainudiin/scalable-data-science,lamastex/scalable-data-science,lamastex/scalable-data-science,lamastex/scalable-data-science,raazesh-sainudiin/scalable-data-science,lamastex/scalable-data-science,raazesh-sainudiin/scalable-data-science,raazesh-sainudiin/scalable-data-science,lamastex/scalable-data-science,lamastex/scalable-data-science