This is a list of my top 10 freely available papers on the topic of information retrieval. You will notice that they are rather old, but the techniques used described and the findings are not always dated. Those that dated are important nonetheless because they provide a good foundation to understanding why things are as they are in information retrieval these days.
Using linear algebra for intelligent information retrieval by Michael Berry, Susan Dumais and Gavin O’Brien (1995)
A Taxonomy of Web search by Andrei Broder
The seven ages of information retrieval by Michael Lesk
Information retrieval data structures and algorithms by William Frakes and Ricardo Baeza-Yates (1992)
Simple, proven approaches to text retrieval S.E. Robertson, K. Sp¨arck Jones (1994)
Information retrieval on the world wide web by Venkat Gudivada, Vijay Raghavan and William Grosky
Lexical ambiguity and information retrieval by Bruce Croft and Robert Krovetz (1992)
The INQUERY Retrieval System by James Callan, Bruce Croft and Stephen Harding (1992)
Term weighting approaches in automatic text retrieval by Gerard Salton and C Buckley (1987)
2 great books you can plough through online about IR:
Information Retrieval by van Rijsbergen (1979)
Introduction to information retrieval by Christopher Manning, Prabhakar Raghavan and Heinrich Schuetze
Why should you care?
The reason for caring is the same for SEO professionals and for computer scientists. Reading about the beginning allows you to understand the present in more depth. Not knowing why a certain method was applied to information retrieval in the 1st place allows for limited understanding as to why they are used today. I suppose it’s a history lesson in some ways but the some of the importance lies in the fact that many of these techniques and variants of them are still used today.