For accurate pronunciation if you read Sanskrit.
Look for scanned books titled Gitartha Samgraha with English Translation and Notes or Gita Bhashya of Ramanuja (which usually includes Yamunacharya’s verses at the start of each chapter). gitartha sangraha yamunacharya pdf
Sri Yamunacharya was a brilliant philosopher-saint and the grand-guru of Sri Ramanujacharya. Before renouncing his kingdom to lead the Sri Vaishnava community, he was a victorious king known as Alavandar. For accurate pronunciation if you read Sanskrit