all persons must read books named : "ek onkar satnam a book on sikhism" author dr. narinder nirchhal, publishers diamond pocket books (p) ltd. new delhi. website www.dpb.in (in english)
(2) "guru nanak dev ji dian varan : saroop ate vishleshan" author dr. narinder nirchhal, publishers gurmat parkashan, patiala.
email : gurmatparkashan@yahoo.co.in. (in punjbi)