Julfiker Hossain

http://bida.gov.bd/?page_id=1914#wpcf7-f5118-p1914-o1 

https://developers.facebook.com/docs/messenger-platform/discovery/facebook-chat-plugin#steps

http://esdp.gov.bd/?fbclid=IwAR0UIlt_DrllorxoSdbTwWivA6PjrQvAfpPT514VSGisboObZmdxvpArkj0