A perennial problem at our school. Although the boys are taught about how to write bibliographies, they inevitably forget how to do it correctly, especially for the web-based resources. A few years ago, after we had practised writing bibliographies I showed the boys the Citation machine. It is now upgraded to Son of Citation Machine. I have not used this lately because I did not want to put in more information to another system.
Last week I found a new citation machine called EasyBib. EasyBib is an automatic bibliography generator that is very easy to use. There is a tutorial that might be useful to younger students but it is really easy to figure out. You can also subscribe to a professional account but it is not necessary to obtain a basic sitation. When you select the source for a long list you go to a screen that has fields that prompt you you to enter the data needed.
One great little option is to use the ISBN of a book to do an easy citation. EasyBib gets the information and when you click next it is ready for you to copy.
It takes away a lot of the worry students have about what infomation should be put in for what source. Some seem to think that, if they are not sure, the best thing is not to cite that information source. This makes it easy for them to do the right thing. I will add this link to my library page so the boys will always know where to find it, along with the other information about writing bibliographies.