var osm = L.tileLayer('http://a.tile.openstreetmap.org/{z}/{x}/{y}.png', {
attribution: 'Map data © <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, <a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>',
maxZoom: 18
});
var oa_summer = oam.api.tilelayer(L, 'oa_map');
var oa_winter = oam.api.tilelayer(L, 'oa_map_winter');
var mymap = L.map('mapid', {
center: [47.546, 10.292],
zoom: 13,
layers: [oa_summer]
});
L.control.layers({
"Outdooractive Summer": oa_summer,
"Outdooractive Winter": oa_winter,
"OpenStreetMap": osm
}).addTo(mymap);