A fifth way is that WebCite ® may have (on request of the cited author/publisher) assigned a DOI to an archived snapshot, so that the link has the format http:////" (where xxx is the hash key of the material in WebCite ® ). The DOI resolver at (which is commonly also used to resolve cited journal and book references) would then resolve to a WebCite ® page (or an intermediary page pointing to the same work in other archives, to other manifestations such as print or pdf, or - in the case of online preprints - to "final" publications).
While I have nice handwriting and some experience with hand-lettering, I knew if I got too precious about layouts and color-coding, I'd be less likely to actually do it. After I was a month into bullet journaling, and was sure it was a habit that was going to stick, I felt OK adding some color. Then a couple months later I started doing more involved weekly layouts . But it's totally, totally fine to take a more minimalist approach. (I also only use color on the headers/flair so if, say, I forget my green pen, I can just use pencil as a placeholder.)