Muhammad Salih Al-Munajjid
www.islamqa.info - Islam : Question & Answer Website
A useful article mentions mistakes made when entering ihraam for Hajj on the day of Al-Tarwiyah.
Mistakes made when entering ihraam for Hajj on the day of al-Tarwiyah
Is the Udhiyah Obligatory for the Pilgrim Doing Hajj?
The Fiqh Of Hajj
Hajj - Points of Benefits
Hajj & Umrah from A to Z