https://web.archive.org/web/20140627022042/http://www.chesscafe.com/text/hansen153.pdf
https://www.newinchess.com/media/wysiwyg/product_pdf/7777.pdf
https://www.newinchess.com/media/wysiwyg/product_pdf/7030.pdf
https://www.everymanchess.com/downloadable/download/sample/sample_id/108/
ruy lopez(white)
scandinavian, modern(black)
nimzo indian
bogo indian