1 peso "In Ps"
... that one of the world's great philatelic rarities, the 1 peso "In Ps" tête-bêche pair , is the only known copy of the State of Buenos Aires 1859 Barquitos postage stamp error?
... that one of the world's great <a href="./Philately" id="mwDgQ" rel="mw:WikiLink" title="Philately">philatelic</a> rarities, the <b id="mwDgU"><a class="mw-redirect" href='./Buenos_Aires_1859_1p_"In_Ps"_tete-beche_pair' id="mwDgY" rel="mw:WikiLink" title='Buenos Aires 1859 1p "In Ps" tete-beche pair'>1 peso "In Ps"</a></b> <a href="./Tête-bêche" id="mwDgc" rel="mw:WikiLink" title="Tête-bêche">tête-bêche pair</a> <i id="mwDgg">(pictured)</i>, is the only known copy of the <a href="./State_of_Buenos_Aires" id="mwDgk" rel="mw:WikiLink" title="State of Buenos Aires">State of Buenos Aires</a> 1859 <i id="mwDgo">Barquitos</i> <a class="mw-redirect" href="./Postage_stamp_error" id="mwDgs" rel="mw:WikiLink" title="Postage stamp error">postage stamp error</a>?