If you're interested in perl's data structures, there is also PerlGuts Illustrated which probably won't make sense unless you read it along with perlguts, but adds a lot of details that will be useful if you want to explain (and understand) it in depth.

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-DA
> perl -MPOSIX -e'$ENV{TZ}="US/Eastern";print ctime(10**9)'
Sat Sep  8 21:46:40 2001
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