Which of these sources should I rely on?

* Heat and Dust.
BFI-British Film Institute: 1982
http://ftvdb.bfi.org.uk/sift/title/229608?view=release
Rottentomatoes: 1982
http://www.rottentomatoes.com/m/heat_and_dust/
Blockbuster: 1982
http://www.blockbuster.com/catalog/movie/similar/15073
IMDb: 1983
http://www.imdb.com/title/tt0084058/releaseinfo

* Go for Broke!
BFI-British Film Institute: 1950
http://ftvdb.bfi.org.uk/sift/title/34893?view=release
Rottentomatoes: 1951
http://www.rottentomatoes.com/m/1008429-go_for_broke/
Blockbuster: 1951
http://www.blockbuster.com/catalog/movieDetails/13639
IMDb: 1951
http://www.imdb.com/title/tt0043590/

* Escape from Angola, aka Return to Africa
BFI-British Film Institute: 1977
http://ftvdb.bfi.org.uk/sift/title/460220
Rottentomatoes: 1977
http://www.rottentomatoes.com/m/return_to_africa/
IMDb: 1976
http://www.imdb.com/title/tt0074492/

* The Devil's Cavaliers, aka I Cavalieri del Diavolo
Rottentomatoes: 1958
http://www.rottentomatoes.com/m/devils_cavaliers/cast_crew.php
IMDb: 1959
http://www.imdb.com/title/tt0052684/releaseinfo

One more.

The Mark of the Hawk
BFI: 1957
http://ftvdb.bfi.org.uk/sift/title/41984?view=release
Rottentomatoes: 1958
http://www.rottentomatoes.com/m/mark_of_the_hawk/
IMDb: 1957
http://www.imdb.com/title/tt0050692/

Quoting AESP_pres:

Quote:
Just check the copyright info at the end of the movie this is the most reliable source. Do this with all of them before going to an online source. It seems evident for me ...

Still, the Rules request us to enter the year of the first public show, not the year of copyright.

Quote:
Production Year 
Enter the year of the original theatrical release.

Quoting EnryWiki:

Quote:


Still, the Rules request us to enter the year of the first public show, not the year of copyright.

Quote:
Production Year 
Enter the year of the original theatrical release.

And it's the same thing in 99.94% of the case. I don't see the need to run at another source for everything. I rarely use an outside source when I contribute a new profile, almost everything I need are in the material at hand (the movie, the extra, the commentary, ...).

Quoting northbloke:

Quote:
While it's true that we don't use the copyright year, it can still sometimes give you a clue as to which one will be right.
For example, if the Go For Broke! copyright year is 1951, then obviously the BFI database is wrong. Of course if it says 1950, then you're pretty much back to square one! 

It says 1950. 

Quoting skipnet50:

Quote:
Then BFI database is wrong, they are not going to show something publicly which is not protected by Copyright, enry, even 57 years ago.

Skip

I had your same thought (if I understand correctly what you mean). Yes, of course the movie does have a copyright indication. I read it in the opening titles and it says "Copyright MCML", id est 1950, as I reported before.
But then it occured to me that BFI probably means that the copyright date is "Not available" in their  database, not that there is no copyright.

Quoting skipnet50:

Quote:
if Blockbuster and RottenTomatoes are licensing IMDb data,

*Apparently* not, as their data differ from IMDb sometimes.

Quoting AESP_pres:

Quote:

And it's the same thing in 99.94% of the case. I don't see the need to run at another source for everything. I rarely use an outside source when I contribute a new profile, almost everything I need are in the material at hand (the movie, the extra, the commentary, ...).

It's harder for old movies! For instance, in Warhead, aka The Prisoner in the Middle, the titles are almost illegible, the copyright year is 197... something... can't read the last digit, perhaps a "3", not sure.
And if I search the online databases, I am at a loss!

IMDb 1977
RT 1975
BFI 1975
Blockbuster.com 1974

I can only say that it might be 1975 because 2 databases out of 4 show that year.