Doctor Who and the Keys of Marinus (novelisation)

The Voord are identified as a frog-like subspecies with bullet-shaped heads, lacking their distinctive helmets.
The warrior who initially follows Susan around the outside of the City is a "Class 1 Voord Assault Trooper" that has been programmed to kill enemies on sight, indicating that it is partly mechanical or robotic in nature.
Yartek is said to have developed a technological immuniser that he distributed amongst his followers rather than the unexplained resistance to the Conscience's pacifying influence of the televised version.

Writing and publishing notes

This title was Philip Hinchcliffe's last contribution to the range and his sole novelisation of a serial he did not produce.
With no photographs for reference, cover artist David McAllister decided to try something different and feature no people on the cover.
Then producer John Nathan-Turner's insistent critique of the cover artwork -- namely that the TARDIS itself is blue, not grey and the light atop it white, not red -- went unheeded. The unaltered image was used for publication.

The passage of time on Marinus is measured in zeniths.
The Voord's origins here as genetically-engineered animals conflict with other sources that position them as early ancestors to the Cybermen. (COMIC: The World Shapers)

First publication:

W.H.Allen & Co. Ltd. UK

Target

Re-issues:

A planned reissue in 1994 was cancelled.

to be added