BBC
Bbc News: Pakistan's Army and Its History of Politics
This site from BBC News contains a medium sized article in Pakistan's History in Military. About half-way down the article is a somewhat comprehensive exploration of Pakistan's military coup, led by Mohammad Ayub Khan in 1958.
Other
Bernard Safran Time Magazine: Mohammad Ayub Khan
A portrait of Muhammed Ayub Khan, President of Pakistan, during his presidency from 1960-1969. This site includes a link to several Wikipedia entries on Khan as well for further research.