by the last names of authors
Yes, authors should be listed in alphabetical order for APA citations.
Yes, you do put a period after "et al." in citations.
You put things in alphabetical order
yes you can, as long as you use them to support - not replace - your own conclusions. And since it is your conclusions that count here, use citations here sparingly and put the rest elsewhere in your essay.
In exactly that order if you mean alphabetical.
Alphabetical according to the surname of the author.
It depends on what order you want. In alphabetical order, they'd go like this: what, when, where, which, will, and would.
Just put all your citations at the end of your essay. In text citations should be at the end of the paragraph.
To give credit to sources
he put them in alphabetical order
he put them in alphabetical order
Citations