Find inside callback of another find (...), how to escape from callback hell?

(First: I'm sorry, I don't speak english very well!)

I wanna return the results of 3 finds in one array. My code (next) is running well, but I'm in callback hell!

_Schema
  .static('retrieveAll', function(cb) {
    query = {};
    this.find(query, function(err, data) {
      if(err) {
        cb(err, null);
        return;
      }

      if(data)
        all = data;
      else
        all = [];

      _StoresModel.find(query).select('contact address').exec(function(err, data) {
        if(err) {
          cb(err, null);
          return;
        }

        if(data) {
          all = data.reduce(function(coll, item) {
            coll.push(item);
            return coll;
          }, all);
        }

        _CustomersModel.find(query).select('contact address').exec(function(err, data) {
          if(err) {
            cb(err, null);
            return;
          }

          if(data) {
            all = data.reduce(function(coll, item) {
              coll.push(item);
              return coll;
            }, all);
          }

          cb(null, all);          
        });
      });
    });
  });

I've a FIND inside a FIND inside a FIND. Is there anyway to improve this?