Triplanetary

also by E. E. 'Doc' Smith in our collection:

• Children of the Lens (Lensman Series)
• First Lensman (Panther Science Fiction)
• Galactic Patrol (Panther Science Fiction)
• Grey Lensman (Panther Science Fiction)
• Second Stage Lensman (Lensman Series)
• Masters of the Vortex (Lensman Series)