Crammed means completely fill (a place or container) to the point that it appears to be overflowing or study intensively over a short period of time just before an examination. The word crammed mostly means to fill (something) by force with more than it can easily hold. to force or stuff (usually followed by into, down).
The inclusion of reputable sources and specific facts would best strengthen the author's main argument because it would offer factual proof instead of just the author's opinion on the matter.
