Linear And Branching Series

Linear Future History Series by Poul Anderson

Psychotechnic: a Heinleinian time chart

Technic: historical cycles

Maurai: post-nuclear Earth

Flying Mountains: asteroid colonisation

Rustum: extra-solar colonisation

Kith: interstellar trade

Harvest Of Stars: human-AI interaction

Genesis: post-human AI

Linear Future History Series by James Blish

Cities In Flight: flying cities

The Seedling Stars: Adapted Men

Branching Future History Series by James Blish

Haertel Scholium: 

Lithia (a sinless planet);

"Angels" (energy beings); 

Dirac transmitter (an instantaneous communicator);

Galactic Cluster trilogy (microcosmic telepathy).

I am rereading A Case Of Conscience, about Lithia. This novel refers back to Haertel but is not and does have to be consistent with other Haertel Scholium works. 

When we reread a book decades later, it is like a different book.