Here are some options and their nuances:
Direct Translations:
* "Iniingatan para sa sanggunian" - Literally "kept for reference." This is a very formal and direct translation.
* "Napanatili para sa sanggunian" - Similar to the above, but emphasizes the act of preserving for reference.
More Specific Options:
* "Iningatan bilang sanggunian" - "Kept as a reference"
* "Pinananatili bilang sanggunian" - "Preserved as a reference"
* "Para sa pagsanggunian" - "For reference" (often used in phrases like "naging sanggunian" - "became a reference")
Contextual Alternatives:
The best translation will depend on the context. For example:
* If you're talking about physical documents: "Iniingatan bilang dokumento" (Kept as a document)
* If you're talking about digital data: "Napanatili bilang data" (Preserved as data)
Informal:
* "Para ma-refer" - "For reference" (informal and commonly used)
Remember, the best option is the one that best captures the intended meaning in your specific context.