Sources:

1. Horton [confirmed]
   http://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736%2815%2960696-1.pdf

2. Angell [confirmed]
   http://www.nybooks.com/articles/archives/2009/jan/15/drug-companies-doctorsa-story-of-corruption/
   Horton's and Angell's quotes also referenced here:
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4572812/#b2-cvj_10_1011

3. Relman [likely untrue]
   Wikipedia and other sources reference this 2002 New Republic article:
   https://pubmed.ncbi.nlm.nih.gov/12561803/
   Here's the full text (publicly accessible PDF): https://facultystaff.richmond.edu/~bmayes/pdf/relmanangell_Rxdrugs.pdf
   While the article is sufficiently damning, this exact quote is just not there.

4. Pauling [confirmed with minor correction]

Everyone should know that the "war on cancer" is largely a fraud, and that the National Cancer Institute and American Cancer Society are derelict in their duties to the people who support them."
https://paulingblog.wordpress.com/2008/10/28/clarifying-three-widespread-quotes/