Web Resources:
Interactive IPA chart: http://www.ipachart.com/
Language Creation Society: https://conlang.org/
ConLang Reddit: https://www.reddit.com/r/conlangs/wiki/resources
How to Make a ConLang: https://www.youtube.com/watch?v=FHK1gO2Mh68&feature=emb_logo
Klingon Language Institute: https://www.kli.org/about-klingon/klingon-phrases/
E-books:
Sacred Languages of the World
https://onlinelibrary.wiley.com/doi/book/10.1002/9781119234661
The Languages of the World
https://ebookcentral.proquest.com/lib/kutztown-ebooks/reader.action?docID=170209&ppg=1
Esperanto and Its Rivals
https://ebookcentral.proquest.com/lib/kutztown-ebooks/detail.action?docID=3442520
Interlinguistics: Aspects of the Science of Planned Languages
https://search.ebscohost.com/login.aspx?direct=true&AuthType=sso&db=nlebk&AN=558780&site=ehost-live&scope=site&custid=s3915793&ebv=EB&ppid=pp_Cover
Subject Headings (Search Terms)
Language – Glossaries, etc
Imaginary language in literature
Imaginary languages
Languages, artificial
Also use names of known artificial languages such as: Ido, Esperanto, Klingon, Blissymbolics, Lojban, Loglan, etc.