What does OS-21 stand for?
OS-21 stands for "Observing System - 21st Century"
How to abbreviate "Observing System - 21st Century"?
"Observing System - 21st Century" can be abbreviated as OS-21
What is the meaning of OS-21 abbreviation?
The meaning of OS-21 abbreviation is "Observing System - 21st Century"
What does OS-21 mean?
OS-21 as abbreviation means "Observing System - 21st Century"
