If you've been wondering whether it's okay to paint with oils over acrylics, you'll find the answer in this Oil Painting Problem Solver.
Oils vs acrylics left is oil, right is acrylic. : r/minipainting
Painting with Oils Over Acrylic -- Is it Okay?
Sea Dean - Paint a Masterpiece: HOW DO I TELL IF A PAINTING IS OIL OR ACRYLIC?
How to prime paper and cardboard for oil painting
Should You Paint Oils Over Acrylics? - Malcolm Dewey Fine Art
Which Paint? An introduction to oils, acrylics, watercolour and pastel - Jackson's Art Blog
Tips for oil painting on paper (and the best paper to use)
Painting with Oils Demystified
Dramatic Clouds and Subtle Skies in oil or acrylic — Andy Eccleshall Fine Art
How to Start Over on an Oil Painting - Helpful Tips for Artists