I am interested to know the standard sources (reports / websites / research articles) which can be refereed to know the precise years in which El Nino, La Nina, Positive IOD and Negative IOD impacted Indian Monsoon between 1970 to 2016.
The BoM maintains a good record of IOD-positive/negative years (http://www.bom.gov.au/climate/iod/) which is good for an overview; though I prefer the more detailed analysis from JAMSTEC (http://www.jamstec.go.jp/frcgc/research/d1/iod/HTML/Dipole%20Mode%20Index.html).
Again for ENSO, the BoM has a good overview (http://www.bom.gov.au/climate/enso/enlist/index.shtml, with links for La Nina therein), as does NOAA (https://www.esrl.noaa.gov/psd/enso/mei/); if you want something more detailed in terms of numbers, I would recommend the CPC (http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml).