The GPL does require you to keep any existing copyright notices:
- You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you [...] keep
intact all the notices that refer to this License and to the absence
of any warranty [...]
The GPL also recommends adding a notice to each file:
Copyright (C) yyyy name of author - This program is free software[...]
From my reading of the GPL, if the software you modify contains such notices, which is likely, you must preserve them. This effectively attributes the original author.
However, as far as I can see, there is no requirement to have a list of acknowledgements (as is customary in scientific papers), which lists all the software you used.
How to attribute parts that are integrated in source form? (Where
licence information is given in the file header)
If you keep the original file header (and possibly add to it), that should be enough.
How to attribute parts that are integrated in binary form?
As far as I can see, there is no additional attribution required for distribution in binary form. The GPL requires you to supply the source code along with the binary form, so the attribution in the source code will be available.