Here are some links to World Witches Series related resources
Official Websites
Strike Witches Operation Victory Arrow
Suomus Misfits Squadron ReBOOT
World Witches Niconico channel
Other Websites
EWACS - Humikane Strike Witches blog, witches profiles can be found here
A collection of old SW related tweets from Humikane
Firstspear Africa series website
Official Twitter Feeds
Strike Witches Road to Berlin Twitter
World Witches United Front Twitter
Other Notable Twitter Feeds
Humikane's Twitter - The original creator of the World Witches Series
Yamibun's Twitter - The military/reference advisor of the anime
Nogami's Twitter - One of the author of the Africa series
Noboru Yamaguchi's Twitter - The author of the Misfits novels
Hukugouzaihibi's Twitter - The author of Hukugouzaihibi fc2 blog (SW news, releases, official art...)
Fanbase Related Other Stuff
English Strike Witches Wikipedia page
Hukugouzainahibi's blog - Strike Witches news, releases, official arts, etc.