Paradoxes of Material Implication  
   Lecture notes by Peter Suber.
   http://www.earlham.edu/~peters/courses/log/mat-imp.htm

Relevance Logic  
   Article in the Stanford Encyclopaedia of Philosophy, by Edwin Mares.
   http://plato.stanford.edu/entries/logic-relevance/

Faithful and Fruitful Logic  
   Article by John Howes, presented at the 20th World Congress of Philosophy.
   http://www.bu.edu/wcp/Papers/Logi/LogiHowe.htm

Conditionals and Counterfactuals  
   Essay by Hector Parr, considering some philosophical difficulties with `if'.
   http://www.c-parr.freeserve.co.uk/hcp/if.htm

Nomic Dependencies & Contrary-to-fact Conditionals  
   Essay by William S. Boardman discussing Fred Dretske's measles examples in his book `Knowledge and the Flow of Information'.
   http://www.lawrence.edu/fac/boardmaw/contr_cond_nomic.html

Conditional Sentences  
   Lecture notes on the analysis of condition sentences by Paul Kay.
   http://www.icsi.berkeley.edu/~kay/bcg/lec07.html

Peirce and Philo  
   Discusses Charles Peirce's account of conditionals, hypotheticals, and what he takes from Cicero's account of the debate between Philo and Diodorus.
   http://www.clas.ufl.edu/users/jzeman/peirce_and_philo.htm