Country Studies - A series of 80 books by the U.S. government giving overviews (from an American perspective) of countries around the world and their political, economic, and security situations. Most were written in the 1980s, with many of the online editions including updates into the 90s.
City Population Statistics: A database of country, province/state, county, and city populations, both before and after Doomsday. Useful for estimating populations.
PC Library Map Collection - Collection of maps of the countries of the world by the University of Texas. This include many maps created in the mid70s, pretty useful.
Paper on Indian Fertiliser Industry - A paper from 2000 showcasing the growth and breakdown of India's fertiliser industry and the different components involved in it
Fanack - Organization that provides information on water resources of the Middle East
Nuclear Warfare 101, 102, and 103 - Information on doctrine in the event of a nuclear war and possible repercussions, as well as information on how nukes work.
Nuclear Forces Guide - Capabilities and strategic doctrines of each of the nuclear-armed states.
Chinese Nuclear Forces and US War Planning - A dossier regarding Chinese's nuclear aim and defence strategy, alongside it's history and also the defensive plans of the US.
Helicopter and ships database - A website with a database of military ships with important events and dates, alongside other informations.
NUKEMAP - an incredibly useful tool giving everything from casualty reports to fallout levels and direction, created by Alex Wellerstein.
Nuclear Attack Planning Base - A report compiled in 1987 about a possible nuclear war over the United States by the Soviets.
Prima Guerra Globale mappa - A google map created for showing the efforts of a nuclear war, done by the Unione scienziati per il disarmo, a scientific group with the goal of avoiding nuclear war. (Done in 1983)
Quora answer - An answer on whether nuclear missiles can be intercepted mid flight.
Reddit answer - Another answer on whether nuclear missiles can be intercepted.