On Heathen Worldview:
The Culture of the Teutons, Vilhelm Grønbech
The Sacred & The Profane, Mircea Eliade
The Meadhall, Stephen Pollington
On the Spirits of the Land, Home, and Ancestors:
The Tradition of Household Spirits, Claude Lecouteux
Demons and Spirits of the Land, Claude Lecouteux
Phantom Armies of the Night, Claude Lecouteux
On the Gods:
The Elder Gods, S. Pollington
Valuable Reference Materials:
Dictionary of Northern Mythology, Rudolf Simek
Encyclopedia of Norse & Germanic Folklore, Claude Lecouteux
There are many other books and academic papers I’ve gathered great insight and knowledge from but I hate when starter/foundational booklists are a mile long! I’ll be featuring some of these additional sources in blog posts over time.