 Complete the following phrase:  The first Serbian record of the assassination of the Ottoman Sultan Murad I was the Life of Despot Stefan Lazarević by Constantine of Kostenets, although the name of the executor was not mentioned. The heroic image of the Battle of Kosovo and the cult of Lazars martyrdom has lost its force over time. The epic expression of the Battle was cultivated in the emigration of Serbs to the mountainous regions of Old Serbia, Montenegro and Herzegovina. Following the 