Which one is correct?
"phenomenon" or "phenomenons"?

Some examples from the web:

• A third phenomenon was that of price compensation.
• Actually, our mandate is any unexplained phenomenon.
• One promising human technology currently being researched might explain such phenomenon.
• But that phenomenon appeared in another place.
• Chronic hunger seems a completely normal phenomenon.
• Very often organised crime stands behind this phenomenon.
• Voluntary work and NGOs represent a growing phenomenon in society.
• Combating this phenomenon therefore requires political and social mobilisation.
• Globalization is a much complex phenomenon that requires fitting political institutions.
• Germany shows us the clearest example of this phenomenon.
• Then what we saw tonight was a physical phenomenon.
• Japan's experience illustrates this phenomenon perfectly.
• Holocaust denial is part of this phenomenon.
• Disability is not a static phenomenon.
• Superconductivity is a phenomenon observed in several metals and ceramic materials.
• That extension is a pure phenomenon.
• Lombardi's painting is a critical phenomenon.
• Mass tourism is a modern phenomenon.
• Leopoldo Nobili first observed this phenomenon in 1828.
• Simple examples of this social phenomenon are make-up and clothes.

Some examples from the web:

• Phenomenons may also be used as the plural in nonscientific writing when the ... occurrences, or persons": They were phenomenons in the history of music.
• b plural phenomenons : an exceptional, unusual, or abnormal person, thing, or occurrence. See phenomenon defined for English-language learners.
• Feb 17, 2014 ... 4 Responses to “50 Incredible Natural Phenomenons”. supercorm says: February 17, 2014 at 8:35 am. What … magnetic north ?! Interesting …
• [fi-nom-uh-nuh] /fɪˈnɒm ə nə/ (Show IPA), or especially for 3, phenomenons. 1. a fact, occurrence, or circumstance observed or observable: to study the ...