Horizon Alpha Douglas R. Mason PB 1st Ballantine (1971)

Dilation Effect Douglas R. Mason PB 1st Ballantine yellow dot

Moons Of Triopus John Rankine aka Douglas R Mason PB 1st Paperback Library 1969

Satellite 54 Zero Douglas R. Mason PB 1st Ballantine (1971)

Dilation Effect Douglas R. Mason PB 1st Ballantine (1971)

Ring of Violence Douglas R. Mason PB 1st Avon (1969)

b Douglas R Mason EIGHT AGAINST UTOPIA 1967 First Paperback Library

Eight Against Utopia Douglas R. Mason PB 2nd Paperback Library (1970)