Revealing the Mysteries of Heaven
The Coming Golden Kingdom Age
both above books by Dr. David Jeremiah
https://www.davidjeremiah.org/
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Heaven
above book by Randy Alcorn
https://store.epm.org/
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Angels
above book by Billy Graham
https://billygraham.org/
You can get the book at https://www.thriftbooks.com/
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Angels
above book by David Jeremiah
https://www.davidjeremiah.org/store/product/angels-who-they-are-and-how-they-help-0852
This book has a study guide as well [separate]