I use this one:
FUJIYAMA BRAND "ORGANO-GRO" An extremely great Organic Fertilizer from Japan.
Organic Pellet Fertilizer
Fujiyama Brand - ORGANO GRO - An Excellent Japanese Organic Fertilizer for use with your Bonsai and all Plants. We purchase this high quality product in very large bags and then repackage it into an much more affordable size for our customers. You will be very happy with this product as it gives you many of the key ingredients that the more expensive products offer. Please check out the details about fertilizers at the top of this page. Major Fertilizer Elements NitrogenN4% of total weightPhosphorus

6% of total weightPotassiumK2% of total weight Minor Elements IronFe543 mg/kgManganeseMn67 mg/kgZincZn71 mg/kgCopperCu8 mg/kgSodiumNa.2% of total weightMagnesiumMg.6% of total weightCalciumCa5.3% of total weight
http://www.dallasbonsai.com/store/fertilizers.html