What are the "must read" academic articles every GIS professional should read?

Having spent some time recently talking with teaching staff regarding new GIS students one of the things that most students seem to be lacking is a sound understanding of database theory and data storage and management practices.

I realize it is not a glamorous subject, but a good grounding in database theory will go a long way towards reducing errors in the design and implementation of geodatabases which can be the bane of many projects.

To that end I would recommend the two papers which I believe provide an excellent grounding in data modelling and database design:

• Bill Kent's 1980 paper on normal form (PDF)
• Peter Chen's 1976 paper on ER modelling (PDF)

Of course these two papers are built on the work of the great Ted Codd, to whom we all owe a debt of gratitude. And every student should learn the oath:

Every non-key attribute must provide a fact about the key, the whole key, and nothing but the key, so help me Codd

For label placement, Eduard Imhof, 1975. “Positioning Names on Maps”, “The American Cartographer”, volume 2, no. 2. pp. 128-144 (PDF).

Ian McHarg's Design With Nature is often credited as having laid many of the foundations of GIS.

Arguably, Ian McHarg’s 1969 landmark book Design With Nature has had a greater influence on the development and application of Geographic Information Systems than any other single event in GIS history. "McHarg's Method" describes how, thorough and multidisciplinary analysis of a region's ecological sensitivity, different information can be layered and combined geographically to identify suitability for different types of development and use. Design With Nature discusses the effects of what we now called sprawl and advocates a means of sustainable development. Today, McHarg's approach, the polygon overlay, forms the basis of many complex analyses and reports performed with (GIS).

(Source: http://www.urisa.org/hall/mcharg)