Litt and Luty. 1989. A hypervariable microsatellite revealed by in vitro amplification of a dinucleotide repeat within the cardiac muscle actin gene. American Journal of Human Genertics. 44 (3): 397-401. www.ncbi.nlm.nih.gov/pmc/articles/PMC1715430/pdf/ajhg00113-0101.pdf