Get ready for an alien invasion with these covers from artist H.R. Van Dongen.  Born in New York and trained in commercial art at the Mechanics Institute, Van Dongen served in the U.S. Air Force during World War II and spent eleven months in a German POW camp.  After being liberated in 1945, Van Dongen returned to the United States and launched a prolific career as an illustrator.  Though he did covers for all genres, Van Dongen is best remembered for his science fiction covers.  Here are just a few of them: