Hi
In the 2nd picture, the power input is marked "+" and the 0V is marked "GND".
For reference xtals it is common to provide some kind of voltage adjustment, so 1 of the pins might be a Vadjust. My guess is that is what the "4.4V" means
Some reference xtal modules also provide a Vref which can be used to derive the voltage adjustment.
Try powering up the xtal from a current limited psu, set to what is written on the module 12V and 6mA.
First use a dmm and probe the 3 other pins for another 12V or 5V or other voltage.
Then probd the 3 pins with scope for the output.
The last pin must be the Vadjust.
Please consider running the output throught a buffer op-amp to protect the xtal.
Depending on the application, it may also be useful to add a amplifier output stage, there are some high current output op-amps available. Or just build an amplifier stage.