Where can the Christmas poem be found that starts with I carried a King but not the one?

We three camels

poem by Jane Yolen

I carried a king, but not the Child,

through desert storms and winds so wild.

The sands crept into ev'ry pack.

But never did my king look back.

'Forward!' he cried, 'We follow the star,

we do not stop.' So here we are.

I carried a king, but not the One

through searing heat an blinding sun,

through nights so cold my nostrils froze,

and slaves wrapped cloths about my toes.

But forward we went led by a star.

We did not stop, so here we are.

I carried a king, but not the Babe,

and also boxes jewel inlaid.

My packs were stuffed with scents and spice,

the grandest ladies to entice.

No ladies saw we, but only a star.

We did not stop, so here we are.