Deceased father property

Queries pertain to my Agricultural land of Bihar in the name of my father whom the property in discussion has been gifted by his grandfather . In Revenue records the land is currently in the name of my father and rent and lagan taxes are being deposited time to time . I dont have any gift deed copy but i have rent receipt n online record details mentioning the name of my father . My question is > How can i Sell this property ? > I did a search in Sub Registar Office but i couldnt find the gift deed copy . > How can i transfer the property in the name of legal heirs > > Further what documents will be needed . Kindly Help with ur expert opinion . Regds