- PAST ISSUES:
- Summer(2007), Vol. 48, no. 1 in PDF chal4801.pdf (479 kb)
- Spring(2007), Vol. 47, no. 4 in PDF chal4704.pdf (366 kb)
- Winter(2007), Vol. 47, no. 3 in PDF chal4703.pdf (213 kb)
- Autumn(2006), Vol. 47, no. 2 in PDF chal4702.pdf (296 kb)
- Autumn(2004), Vol. 46, no. 2 in PDF chal4602.pdf (294 kb)
- Summer (2004), Vol. 46, no. 1 in PDF chal4601.pdf (212 kb)
- Spring (2004), Vol. 45, no. 4 in PDF chal4504.pdf (289 kb)
- Winter (2004), Vol. 45, no. 3 in PDF chal4503.pdf (491 kb)
- Autumn (2003), Vol. 45, no. 2 in PDF chal4502.pdf (227 kb)
- Summer (2003), Vol. 45, no. 1 in HTML and in PDF chal4501.pdf (212 kb)
- Spring (2003), Vol. 44, no. 4 in HTML (text version) in PDF chal4404.pdf (297 kb)
- Winter (2003), Vol. 44, no. 3 in HTML (text version) in PDF chal4403.pdf (286 kb
- Autumn (2002), Vol. 44, no. 2 in HTML (text version) n PDF chal4402.pdf (361 kb
- Summer (2002), Vol. 44, no. 1 in HTML in PDF chal4401.pdf (223 kb)
- Spring (2002), Vol. 43, no. 4 in HTML also in PDF chal4304.pdf (325 kb)
- Winter (2002), Vol. 43, no. 3 in HTML also in PDF chal4303.pdf (343 kb)
- Fall (2001), Vol. 43, no. 2 in HTML also in in PDF chal0110.pdf
- Summer (2001), Vol. 43, no. 1 in PDF chal0103.pdf
- Winter 2001 in PDF chal4203.pdf
- Summer 2000 in PDF chal4201.pdf
- Spring 2000 in PDF chal4104.pdf
- Winter, 2000, Vol. 41, n. 3 (chal0001.htm) PDF chal0001.pdf
- Fall, 1999, Vol. 41, n. 2 (chal9910.htm)
- Summer, 1999, Vol. 41, n. 1 (chal9907.htm) PDF chal9907.pdf
- Spring, 1999, Vol. 40, n. 4 (chal9904.htm) PDF chal9904.pdf