Where to find the detailed doc of FEniCS legacy?

I want to write a fluid structure problem in FEniCS, and I want to turn to the doc to systemically, after I turn to the legacy FEniCS doc(which is dolfin 1.0 in 2019.1.0) but I find out that there are a lot of functions in that doc only contain the information of the input arguments without the information of the detailed ability and usage of such function, where to find more detailed information?

See: https://fenicsproject.org/olddocs/dolfin/
and pages within for the relevant documentation of any given version