1. APHG Theorists

2. Carl Sauer-Cultural Landscape
Cultural Landscapes have been defined by the World Heritage Committee as distinct geographical areas or properties uniquely "..representing the combined work of nature and of man..“
“The cultural landscape is fashioned from a natural landscape by a cultural group. Culture is the agent, the natural are the medium, the cultural landscape is the result"

3. Johann Heinrich von Thunen-Agricultural Activities Model
The use a piece of land is put to is a function of the cost of transport to market and the land rent a farmer can afford to pay (determined by yield, which is held constant here).
The model generated four concentric rings of agricultural activity.

4. Walter Christaller-Central Place Theory
Hexagons are ideal shapes
settlements simply functioned as 'central places' providing services to surrounding areas.
The higher the order of the goods and services (more durable, valuable and variable), the larger the range of the goods and services, the longer the distance people are willing to travel to acquire them.

5. Homer Hoyt-Sector Model
It is a model of urban land use and modified the concentric zone model of city development
While accepting the existence of a central business district, Hoyt suggested that zones expand outward from the city center along railroads, highways, and other transportation arteries.

6. Ernst Burgess-Concentric Zone Model
This concentric ring model depicts urban land use in concentric rings: the Central Business District (or CBD) was in the middle of the model, and the city expanded in rings with different land uses
Burgess often observed that there was a correlation between the distance from the CBD and the wealth of the inhabited area

7. Harris and Ullman-Multiple-Nuclei Model
It notes that while a city may have started with a central business district, similar industries with common land-use and financial requirements are established near each other.
These groupings influence their immediate neighborhood

8. Halford Mackinder-Heartland Theory
The Heartland lay at the centre of the world island, stretching from the Volga to the Yangtze and from the Himalayas to the Arctic.
"Who rules East Europe commands the Heartland;
who rules the Heartland commands the World-Island;
who rules the World-Island controls the world."

9. Thomas Malthus-Principles of Population
"Malthus argued that population was held within resource limits by two types of checks: positive ones, which raised the death rate, and preventative ones, which lowered the birth rate. The positive checks included hunger, disease and war; the preventative checks, abortion, birth control, prostitution, postponement of marriage, and celibacy."

10. Friedrich Ratzel-Organic Theory of State
States are instead organic and growing, with borders representing only a temporary stop in their movement.
It is not the state proper that is the organism, but the land in its spiritual bond with the people who draw sustenance from it.
The expanse of a state’s borders is a reflection of the health of the nation.

11. Alfred Weber-Least Cost Theory
Alfred Weber formulated a least cost theory of industrial location which tries to explain and predict the locational pattern of the industry at a macro-scale.
It emphasizes that firms seek a site of minimum transport and labor cost.

12. Walt Rostow-Stages of Economic Growth
The model argues that economic modernization occurs in five basic stages of varying length—traditional society, preconditions for take-off, take-off, drive to maturity, and high mass consumption.

13. Immanuel Wallerstein-World-Systems Theory
He characterizes the world system as a set of mechanisms which redistributes resources from the periphery to the core.
In his terminology, the core is the developed, industrialized, democratic part of the world, and the periphery is the underdeveloped, raw materials-exporting, poor part of the world; the market being the means by which the core exploits the periphery.

14. P.J. Taylor and R. E. Lang-World Cities
International, first-name familiarity; whereby a city is recognized without the need for a political subdivision
Active influence on and participation in international events and world affairs
A fairly large population
International Airport
Transportation Network and Financial Institutions
Includes New York City, London, and Tokyo

15. Nicholas Spykman-Rimland Theory
challenges the Heartland Theory; says the Eurasian Rim holds the power to dominate the world; rim includes land that encircles the Heartland and includes China, Korea, Japan, SE Asia, India, the Arabian Peninsula, and Europe

16. Ernst Ravenstein-Gravity Model
The gravity model of migration is therefore based upon the idea that as the size of one or both of the towns increases, there will also be an increase in movement between them.
The further apart the two towns are, however, the movement between them will be less.
This phenomenon is known as distance decay.
Includes Push and Pull Factors