The transistors are not critical, most small signal transistors in a to-92 should be ok.Just check the pinout on the datasheet. For the NPN BC546,547,548,549 A,B or C will all work. Like wise for the PNP 556,557,558,559 are ok. NPN 2n3904 PNP 2n3906 would be another choice.

Konstantin just use the cheapest one. The 20H1736 is ok.

Oh and i don't think the power rating of the Zener was specified on the schematic. It should be 1 Watt.