Concept: Library Management Software is used to automate library functions such as acquisition, cataloguing, circulation, serial control and OPAC.
Step 1: Understand standard library software.
LIBMAN is used for library automation.
LIBSYS is a well-known library management software.
MANDARIN is also used as library automation software.
\[
\text{Library software} \Rightarrow \text{LIBMAN, LIBSYS, MANDARIN}
\]
Step 2: Identify the odd option.
LIBRA is not treated as a standard library management software in the given list.
Step 3: Choose the correct answer.
Since the question asks which is not a library management software, the correct answer is LIBRA.