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We know from the optical/UV emission lines that quasars at high redshift contain heavy elements, at least in the inner few tens of parsecs. But where do these elements come from? Plausibly, from inflow of enriched gaseous material from the inner regions of the quasar's host galaxy. There is only one known quasar at high redshift for which information on such gas is directly available: the Cloverleaf quasar at $z = 2.56$. In the Cloverleaf we have detected strong millimeter-wavelength CO emission lines in several rotational transitions, and also a fine-structure line of neutral carbon. Although the luminosity of these lines is rendered somewhat uncertain by the unknown gravitational lensing amplification factor, there is good evidence for at least $10^{10} - 10^{11}$\ solar masses of molecular material in the inner 2 - 3 kpc surrounding the quasar nucleus. Whether most of the observed C and O were formed in situ, as a result of massive star formation, or were picked up during a merger with another gas-rich system is unclear, but in either case there seems to be a large supply of enriched material available to fuel the quasar if that material can find its way into the center. Introductory material on molecules in low-redshift quasars will be presented, and comparison of the Cloverleaf and the ultraluminous IR galaxy F10214+4724 ($z = 2.3$) will be discussed.
