van de Hulst, Muller & Oort (1954) – The spiral structure of the outer part of the Galactic System derived from the hydrogen emission at 21 cm wavelength
Mohan, Dwarakanath & Srinivasan (2004) – A High Galactic Latitude HI 21cm-line Absorption Survey using the GMRT: II. Results and Interpretation
Mohan, Dwarakanath & Srinivasan (2004) – A High Galactic Latitude HI 21cm-line Absorption Survey using the GMRT: I. Observations and Spectra