MLA

Children Singing as Missionary Sister Plays Piano, Ambato-Boeny, Madagascar, Ca. 1900-1930. 1900. https://collections.library.yale.edu/catalog/11432992.

APA, 6th edition

Children singing as missionary sister plays piano, Ambato-Boeny, Madagascar, ca. 1900-1930. (1900). [Group portraits (AAT), photographic postcards (AAT), photographs (AAT)]. https://collections.library.yale.edu/catalog/11432992.