 Complete the following phrase:  Nikolina Pavlova Shtereva , born 21 January 1955 is a retired Bulgarian middle-distance runner who specialised in the 800 and 1500 metres. She is best known for her silver medal in 800 metres at the 1976 Summer Olympics, and at the European Indoor Championships she won gold medals in 1976 and 1979 and a bronze medal in 