Here's one: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7028023.PN.&OS=PN/702

Here's one: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7028023.PN.&OS=PN/7028023&RS=PN/7028023 http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sec... If you read the claims, doubly linked lists are a special case. However, the prior art for doubly linked lists goes back decades.