I haven't seen a formal list from Lois Lowry herself, but piecing together interviews and her acceptance speeches, she places immense value on the education of living. In her Newbery speeches, especially for 'Number the Stars', she talks about empathy as the writer's core curriculum—understanding history and human choices not from textbooks but from listening to people's stories. She once mentioned that for 'The Giver', her research was less about dystopian theory and more about observing her own father's memory loss, which taught her about the weight and fragility of memory itself.
She seems skeptical of rigid 'how-to' formulas. In a Q&A I read, she advised reading everything, not just current bestsellers, but old letters, diaries, and newspapers to absorb how language and concerns shift. The resource she most explicitly recommends is likely a library card, paired with a notebook for recording the odd, poignant things overheard or personally felt. Technical skill comes from doing the work, but the raw material, for Lowry, comes from a deeply engaged, curious observation of the real, often painful, world.