Armstrong has written four books on investment theory and retirement planning.

Selective investment theory: Recasting the functional significance of close relationships.

George Soros used the word reflexivity, to describe feedback in the financial markets and developed an investment theory based on this principle.

For many years, however, investors had a big question about that investment theory: How can it be put into practice?

I mean does anybody think that parental investment theory is relevant at all to modern industrial society or is it completely irrelevant?

Another theory of creative people is the investment theory of creativity.

He is known for his investment theory of party competition.

Although not explicitly mentioned, the research was ostensibly the investment theory of party competition.

Parental investment theory is a branch of life history theory.