The following list contains publicly available sources.
[Apache Lucene]
https://lucene.apache.org/core/index.html
[Apache Solr]
https://solr.apache.org/guide/8_11/
[Curl]
https://curl.se/
[Lucene Libs]
https://search.maven.org/artifact/org.apache.lucene/lucene-core
https://search.maven.org/artifact/org.apache.lucene/lucene-backward-codecs
[Lucidworks Scaling]
https://lucidworks.com/post/scaling-lucene-and-solr/
[Solr Admin UI]
https://solr.apache.org/guide/8_11/using-the-solr-administration-user-interface.html
[Solr Enable SSL]
https://solr.apache.org/guide/8_11/enabling-ssl.html
[Solr Basic Auth]
https://solr.apache.org/guide/8_11/basic-authentication-plugin.html
[Solr IdxUpgrader]
https://solr.apache.org/guide/8_11/indexupgrader-tool.html
[Solr Installation]
https://solr.apache.org/guide/8_11/installing-solr.html
[Solr Requirements]
https://solr.apache.org/guide/8_11/solr-system-requirements.html
[Solr to Production]
https://solr.apache.org/guide/8_11/taking-solr-to-production.html#service-installation-script
[Wiki DSearch]
https://cwiki.apache.org/confluence/display/solr/DistributedSearch
[Wiki Cron]
https://en.wikipedia.org/wiki/Cron