xml - PHP SOAP request with post method - Stack Overflow
How to Solve SOAP Errors in Magento 2?
PHP - How to set https headers to soap ws request - Stack Overflow
web services - PHP SOAP Extension with WSDL throwing Headers already sent - Stack Overflow
SOAP - Vikipedi
GitHub - phpro/soap-client: A general purpose SOAP client for PHP
Manipulating Soap Web Services With PHP and Laravel - Webmobtuts
GitHub - cansozeri/php-soap-client: A general purpose SOAP client for PHP with interpreting and binding SOAP 1.1 and SOAP 1.2 messages to PSR-7 HTTP messages.
A package that does SOAP the Laravel way (link in comments) : r/laravel