Fretwell, Mattie Bell (February 1937). “The Development if the Thermometer”. 《Mathematics Teacher》 30 (2): 80–83. doi:10.5951/MT.30.2.0080. JSTOR27952013.
Fretwell, Mattie Bell (February 1937). “The Development if the Thermometer”. 《Mathematics Teacher》 30 (2): 80–83. doi:10.5951/MT.30.2.0080. JSTOR27952013.