“His materials vary but his concerns remain the same.  All his sculptures deal with space-space explored and occupied by glowing lines of light. Krebs’ laser lines vanish at the throwing of a switch.  His plastic lines are permanent
but their look is equally insubstantial, luminous and pure…They’re generated by the plexiglass he works with….The planes are colorless, but their edges glow.”  Richard, Paul. 
The Artful Showing of Space, Light and Geometry, The Washington Post, 1969.

“….an exhilarating atmosphere of pure form... his growing mastery both of theory and technique has been an impressive thing to observe…Krebs’ work in plexiglass based upon an ingenious variety of conformations of the right triangle, is stunningly beautiful, a demonstration of the poetry of pure forms.” 
Forgey, Benjamin. ART: the Pure Form of Krebs, The Washington Star, 1969.