Kanji names can be read in different ways, then you need to check with an external source to make sure that's the name of the person. For example, look how many different ways "土山茂三" can be read (copy/paste this name on
WWWJDIC):
* 土山 【つちやま】 Tsuchiyama (p,s) 【つやま】 Tsuyama (s) 【どやま】 Doyama (p,s) NA
* 茂三 【しげぞう】 Shigezou (g) 【きぞう】 Kizou (u) 【しげみ】 Shigemi (u) NA
Also, "土山茂三" may be the same name as another person who has nothing to do with the composer.