As you can read in the given error message
/tmp/.LatexEssay.tex.bbl:8: Undefined control sequence.
l.8 {Worthey}, G. 1994, \apjs
, 95, 107
you have an undefined control sequence \apjs that causes the error. I guess it should contain the name of a journal. So add the line @string {apjs = {The correct name of the journal}} (add the correct name please) to your bib file. With a little pretty printing it could look like this:
@string {apjs = {The correct name of the journal}}
@ARTICLE{1994ApJS...95..107W,
author = {{Worthey}, G.},
title = {{Comprehensive stellar population models and the disentanglement
of age and metallicity effects}},
journal = apjs,
year = {1994},
month = nov,
volume = {95},
pages = {107--149},
doi = {10.1086/192096},
adsurl = {http://adsabs.harvard.edu/abs/1994ApJS...95..107W},
adsnote = {Provided by the SAO/NASA Astrophysics Data System},
}
Did you recognised the -- in field pages?
Above the live preview in Gummi there are tabs named Preview Pane, Build Log, Project, and Bibliography. Click the Bibliography tab. Hit Detect, and references.bib should show up under Filename, with the message "references.bib loaded". Then press Compile. Hopefully that will produce the message "Bibliography complied without errors". Then compile the document twice, and all the references should show up as expected.
Best Answer
You may want to try running Linux software in Windows, this page has info: Five ways to run Linux software in Windows
One of the solutions is called Cygwin and Gummi has been ported to this:
Gummi on Cygwin
I have not tried any of these as I am mainly a Linux guy.
OR
Install a Linux disto on a USB stick, install the latex distribution on the USB stick, install Gummi. Boot your computer with the USB stick to run Linux and Gummi.
Best regards, John