table: tab.tf.overtones        
this table contains fundamental mode frequencies for 0t2 to 0t24
and the first 2 overtone branches.
(all results are from modes studies (mHz) and 
 given with error bars (microHz))

tmodes    : reference value
prem      : anisotropic PREM model, error
R&R       : Resovsky&Ritzwoller, 1998
H&T       : He&Tromp, 1996
WZ&M      : Widmer, Zuern&Masters, 1992
M&W       : Masters&Widmer, 1995
RR&M      : Roult, Romanowicz&Montagner, 1990