There are more than 30 bus operators that operate from Delhi to cities such as Agra , Dehradun , Ghazaibad , Noida ,Most of the buses are increasingly being replaced by sleek and comfortable Volvo buses.

Travellers can book their bus tickets up to one month in advance online or even on their mobiles. Generally people who travel by private buses tend to book their bus tickets one or two days before their journey. So booking bus tickets online or booking bus tickets on the mobile is a very convenient to make bus reservations.

Also cancellation of bus tickets is very easy with online cancellations of bus tickets is offering many online bus ticketing portals.

http://en.wikipedia.org/wiki/Delhi,_India

http://wikitravel.org/en/Delhi

http://www.newdelhiairport.in/traveller.aspx

http://www.india.gov.in/citizen/travel.php

http://www.delhi-university.in/

http://www.delhitourism.nic.in/delhitourism/index.jsp

http://www.delhitourism.com/tourist-office.html

http://www.tripadvisor.com/Hotels-g304551-New_Delhi_National_Capital_Territory_of_Delhi-Hotels.html

http://www.holidayiq.com/states/Delhi-Overview.html