@book{bhlitem59209, title = {Popular scientific lectures }, copyright = {NOT_IN_COPYRIGHT}, url = {https://www.biodiversitylibrary.org/item/59209}, note = {https://www.biodiversitylibrary.org/bibliography/19428}, publisher = {New York, Fitzgerlad, [n.d.]}, author = {Helmholtz, Hermann von,}, year = {}, pages = {56}, keywords = {Education|Germany|Medicine|Optics|Planets|}, }