Art by other artists - famous or not it's always energizing to see someone's art work!
The mini series "The Impressionists" When feeling discouraged artistically, this is good to remind myself to persevere.
Music - I paint best listening to music as it helps me to relax & be loose. Almost any kind is good but usually it's from the 20's & 30's, Big Band Era, The Beatles, The Animals or Classical.
North Light art books & instruction
Quinacridone Coral by Daniel Smith