<a href="https://en.wikipedia.org/wiki/Secretary-General_of_the_United_Nations" id="mwzA" rel="mw:WikiLink" title="Secretary-General of the United Nations">U.N. Secretary-General</a> <a href="https://en.wikipedia.org/wiki/U_Thant" id="mwzQ" rel="mw:WikiLink" title="U Thant">U Thant</a> signs <a href="https://en.wikipedia.org/wiki/United_Nations" id="mwzg" rel="mw:WikiLink" title="United Nations">United Nations</a> proclamation of the vernal equinox as <a href="https://en.wikipedia.org/wiki/Earth_Day" id="mwzw" rel="mw:WikiLink" title="Earth Day">Earth Day</a>.