File talk:110213 LED vs Sodium vs Mercury.jpg
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I can only make out two kinds of lights (circled in the linked Google Drive image), which also makes ambiguous which ones they are, as I can't discern which is "foreground", "background", and "middle". Could the lights be labelled, please? https://drive.google.com/file/d/0B8l25jztUsb8MnBQUVh3Zm9OVFU/view