What was used to bootstrap the C compiler

Question

The C compiler was written in C, that much I know. What language/tools/instructions was/were used to create the initial functionality for the C compiler to become self-hosting?

UPDATE:

I know what bootstrapping a language is, and it is that research that prompted this question. I cannot find an answer to my question anywhere on SO.

Answer 1

There are a multitude of C compilers in the world. Many of them were (and still are) written in C. However the first one was not - it was written in B.