Oracle blogs to refer

https://anuragkumarjoy.blogspot.com/2018/01/step-by-step-procedure-for-applying-psu_30.html

1) http://www.dbacentre.com/oracle-dba-tutorials/

2) http://select-star-from.blogspot.in/2013/07/oracle-dba-interview-questions-answers_2192.html

3)https://sujeetdba.blogspot.in/2015/01/oracle-database-upgrade-11203-to-1210.html

4)http://www.hhutzler.de/blog/crs-doesnt-start-due-to-crs-1714-error/   ----ASM

5)https://databaseinternalmechanism.com/2016/09/22/datapump-export-everything-need-to-know/

6)http://www.runningoracle.com/product_info.php?cPath=84&products_id=226  --scripts


7) http://dbakeeda.blogspot.com/search/label/Performance%20Tuning?updated-max=2017-10-09T13:55:00-07:00&max-results=20&start=6&by-date=false

8) https://oracledbwr.com/oracle-12c-multitenant-database-backup-using-rman/

9) http://facedba.blogspot.com/2017/06/applying-psu-apr-2017-patch-on-oracle.html