Here is a very good link for such repairs:
I use a hot glue gun and very sparingly at that.
When working, the album cover should be placed on a hard clean surface and a book or other heavy object placed on the freshly glued seam so it sets properly.
At one time I used Elmer's white glue and it works, but if the least little bit too much is applied it squeezes out and binds the front and rear of the album and cannot be removed.
Before you use any glue, clean the area well, peeling away all the excess so the new bond is working from fresh paper.
It should go without saying, the LP is put away for this entire operation and if you wish to be extra cautious you can insert a spare dust sleeve inside the art work cover before beginning to provide one additional layer of safety.
Albert, I prefer to use a white PVA adhesive like Elmer's and there's a trick to keeping errant glue from wreaking havoc. Cut a thin sheet of cardboard sized to just barely fit inside the jacket and wrap it with wax paper. Or, you can use silicone release paper like you use to protect a dry mount press platen when you dry mount photographs, it's thicker than wax paper. The non stick surface will protect the inner surfaces from sticking together as the glue dries.
I've always found "Duco Cement" to work well. It's a multipurpose household glue, but it seems to work extremely well for both record covers and split book bindings. Readily available at most hardware stores.
When I ran my used LP store I invested in a double sided adhesive tape gun, not sure if they are still available. It would be the same thickness tape as the inside lip of most LPs(especially European covers)except the hard cardboarded original 60-70's LPs from the US. I found this to be the best method no mess with glues etc and least impact on the covers themselves.
I have glued 100s of these and use Pattex contact glue (sparingly!). Hot melt is more tricky to keep thin and not squeeze out and then in need of trimming etc.
Since usually one side has a foil lining I find contact glue is the best solution --- just DO NOT put the record back in immediately to prevent the vinyl getting in touch with any out-gassing of the glue's solvent (vinyl does NOT like to get 'gassed with thinners :-) I speak from bad experience.
I just use simple Elmer's glue, (the blueish gel kind, not the white stuff) and just put a thin strip on the same line were the old glue was. The I lay a few heavy books on the edge of the cover for a day or so and they always seem to hold up well after that.
It isn't always necessary to glue the whole seam, just up to where it is coming apart. And your right... These DGG/Philips type import covers do come apart sometimes, but fortunatly there easy to fix.
Wow, I can't believe how much time we can spend talking about glue seams! It's no wonder non audiophiles consider us strange. Of course, paper conservers have week long conferences debating this stuff. In any event, Rubber makes a good point about valuable records. Archival glues are far less likely to cause discoloration with the passing years. Contact cements are not archival, although easy to use. PVA (Polyvinyl acetate) glues like Elmer's white and glues designated as archival are not going to cause any problems. Hot glues are also pretty safe too.