Loecher M, Ropkins K. RgoogleMaps and loa: Unleashing R Graphics Power on Map Tiles. J. Stat. Soft. [Internet]. 2015 Feb. 10 [cited 2024 Apr. 27];63(4):1-18. Available from: https://www.jstatsoft.org/index.php/jss/article/view/v063i04