The 2:4 dinitrophenyl hydrazine colour reaction for vitamin K.

@article{REDDY1948The2D,
  title={The 2:4 dinitrophenyl hydrazine colour reaction for vitamin K.},
  author={D SUDHAKARA REDDY and Venkatramanujan Srinivasan},
  journal={Current science},
  year={1948},
  volume={17 1},
  pages={Unknown}
}