1941 article on simultaneous study of two languages

I just registered on JSTOR in order to gain access to this article in its entirety. The article is quite small but the most interesting part is located after the first page so it was well worth it, especially since limited access is free. The basic gist of the article is that when studying two closely related languages, the best thing to do is something like the following:

1) Gain an active proficiency in the first language,
2) Begin to look at the similarities between this and the second,
3) Start studying the second while still keeping the main focus on the first,
4) Keep up a 80 / 20% schedule (those numbers aren't in the article but seem to be about right) with continued active use in the first and passive use in the second,
5) Eventually move to active use in the second language, and if possible having the same teacher in order to keep misunderstandings as few as possible.

With it being 2012 now, it is also quite easy to find identical content in both languages. In this case the recommendation would probably still be to maintain an active focus on Language 1, but to glance over to Language 2 to check where vocabulary and usage is the same or different. The problem here is that differences often come about simply by the translator, and don't necessarily mean that a certain word can or cannot be used. The ideal content to use would be content that specifically points this out, but this is much harder to find.