Make no mistake, I use Wikipedia (and a bit too often at that). And as much praise as I have for it, I think it's fair that I warn people: do your research. What I mean by that is that while using Wikipedia as a resource is a good start, it shouldn't end there.
The strength and weakness of Wikipedia is that nearly everyone can contribute. Unlike encyclopedias which have "professionals" writing those articles, that's not the case with Wikipedia. Of course that's not to say that all the information in Wikipedia is erroneous (or that all the information in an encyclopedia, any encyclopedia, even say The Britannica, is all factual). The problem I think is that there's a mix of facts and not-quite-facts in there--identifying which is which can be troublesome to say the least. But the advantage of a web-based resource is that unlike in print, once an error is spotted, corrections can immediately be made. That's not the case with your 1977 encyclopedia however, which has information three decades outdated.
But I think the problem of Wikipedia stems from the fact that it's written by people--many people. Let's face it, people are biased. History isn't irrefutable. Magellan discovered the Philippines one day, and he didn't decades later (and who knows, he might be attributed to "discovering" a new place or item in the future). Encyclopedias have editorial direction--that is, they focus on one "truth" and stick to it. The same goes with history books. That's simply not the case with a Wikipedia entry. While it's possible that people settle matters amicably, it's also likely that each party will fight for what they believe is "the truth". And I think that's human nature. In the end, there will be various interpretations of events, ideas, and people.
Of course the past three paragraphs is nothing but build-up for the "Wikipedia Contradiction". That is while actual history is disputable, Wikipedia tends to be accurate when it comes to "fictional history" when the topic is covered. What do I mean by fictional history? Well, basically anything from your favorite TV series to your favorite fantasy/science-fiction world to your favorite comic. And perhaps what I'd like to add is that these entries are "accurate" mainly because there's only one source (the text, be it the TV episode, a specific comic issue, etc.) in contrast to reality where there are multiple viewpoints. That's not to say there hasn't been arguments in such entries (and there have been attempts to "vandalize" an entry and skewing it towards a certain fan perspective, such as the pairing of certain characters or whether a person "kicks ass" or "sucks") but rather the "fictional historical events" are undisputed.
What does this all mean? If you're a geek like me, Wikipedia is your best friend. If you're a researcher/scholar, I'd check my sources.