@BOOK{APA,
    AUTHOR = {{American Psychological Association}},
    TITLE = {Publication manual of the {American Psychological Association}},
    PUBLISHER = {Author},
    ADDRESS = {Washington, DC},
    YEAR = {2001},
    EDITION  = {5th}
}

@ARTICLE{Alcock02,
   AUTHOR = {L. Alcock and A. Simpson},
   TITLE = {Definitions:  {D}ealing with categories  mathematically},
   JOURNAL = {For the Learning of Mathematics},
   YEAR = {2002},
   VOLUME = {22},
   PAGES = {28--34}
}

@INCOLLECTION{Anderson01, 
    AUTHOR = {J.~R. Anderson and C. D. Schunn},
    TITLE = {Implications of {ACT-R} learning theory: {N}o magic bullets},  
    BOOKTITLE = {Advances in instructional learning theory: {E}ducational design and cognitive science, {V}ol. 5},
    PUBLISHER = {Erlbaum},
    ADDRESS = {Mahwah, NJ},
    YEAR = {2001},
    PAGES={1--34},
    EDITOR = {R. Glaser}
}

@ARTICLE{Bagno,
   AUTHOR = {E. Bagno and B-S. Eylon and U. Ganiel},
   TITLE = {From fragmented knowledge to a knowledge structure: {L}inking the domains of mechanics and electromagnetism},
   JOURNAL = {American Journal of Physics},
   YEAR = {2000},
   VOLUME = {68{\rm (educational supplement)}},
   PAGES = {S16--S26}
}

@INCOLLECTION{Balacheff88,
AUTHOR = {N. Balacheff},
    TITLE = {Aspects of proof in pupils' practice of school mathematics},  
    BOOKTITLE = {Mathematics, teachers and children},
    PUBLISHER = {Open University},
    ADDRESS = {Kent, UK},
    YEAR = {1988},
    PAGES={216--235},
    EDITOR = {D. Pimm}
}

@INPROCEEDINGS{Bills,
   AUTHOR = {E. Bills and D. O. Tall},
   TITLE = {Operational definitions in advanced mathematics: {T}he case of least upper bound},      
   BOOKTITLE = {Proceedings of the 22nd conference of the {I}nternational {G}roup for the {P}sychology of {M}athematics {E}ducation},
   YEAR = {1998},
   EDITOR = {A. Olivier and K. Newstead},
   VOLUME = {2},
   ADDRESS = {Stellenbosch, South Africa}, 
   PAGES = {104--111} 
}

@ARTICLE{Cobb,
   AUTHOR = {P. Cobb},
   TITLE = {A constructivist perspective on information-processing theories of mathematical activity},
   JOURNAL = {International Journal of Educational Research},
   VOLUME = {14},
   YEAR = {1990},
   PAGES = {67--92}
}

@ARTICLE{Davis92,
   AUTHOR = {R. B. Davis},
   TITLE = {Understanding ``understanding"},
   JOURNAL = {Journal of Mathematical Behavior},
   YEAR = {1992},
   VOLUME = {11},
   PAGES = {225--241}
}


@ARTICLE{Dubinsky94,
   AUTHOR = {E. Dubinsky and J. Dautermann and U. Leron and R. Zazkis},
   TITLE = {On learning fundamental concepts of group theory},
   JOURNAL = {Educational Studies in Mathematics},
   YEAR = {1994},
   VOLUME = {27},
   PAGES = {267--305}
}

@BOOK{Goossens1,
   AUTHOR = {M. Goossens and F. Mittelbach and A. Samarin},
   TITLE = {The {LaTeX} companion},
   PUBLISHER = {Addison-Wesley},
   ADDRESS = {Reading, MA},
   YEAR = {1994}  
}

@BOOK{Goossens2,
   AUTHOR = {F. Mittelbach and M. Goossens and J. Braams and D. Carlisle and C. Rowley},
   TITLE = {The {LaTeX} companion},
   EDITION={2nd},
   PUBLISHER = {Addison-Wesley},
   ADDRESS = {Reading, MA},
   YEAR = {2004}  
}


@BOOK{Gratzer1,
   AUTHOR = {G. Gr\"atzer},
   TITLE = {Math into {TeX}: {A} simple introduction to {AMS-LaTeX}},
   PUBLISHER = {Birkh\"auser},
   ADDRESS = {Boston, MA},
   YEAR = {1993}  
}

@BOOK{Gratzer2,
   AUTHOR = {G. Gr\"atzer},
   TITLE = {Math into {LaTeX}},
   PUBLISHER = {Birkh\"auser},
   EDITION = {3rd},
   ADDRESS = {Boston, MA},
   YEAR = {2000}  
}

@BOOK{Lamport,
   AUTHOR = {L. Lamport},
   TITLE = {The {LaTeX} companion},
   EDITION={2nd},
   PUBLISHER = {Addison-Wesley},
   ADDRESS = {Reading, MA},
   YEAR = {1994}  
}

@ARTICLE{Hanna00,
   AUTHOR = {G. Hanna},
   TITLE = {Proof, explanation and exploration: {A}n overview},
   JOURNAL = {Educational Studies in Mathematics},
   YEAR = {2000},
   VOLUME = {44},
   PAGES = {5--24}
}

@INCOLLECTION{Harel98,
   AUTHOR = {G. Harel and L. Sowder},
   TITLE = {Students' proof schemes: {R}esults from exploratory studies},
   BOOKTITLE = {Research in Collegiate Mathematics Education. {III}},
   EDITOR={A. H. Schoenfeld and J. Kaput and E. Dubinsky},
   YEAR = {1998},
   PAGES = {234--283},
   PUBLISHER={American Mathematical Society},
   ADDRESS={Providence, RI}
}

@UNPUBLISHED{Lester1982, 
    AUTHOR = {Lester, F. K. and Garafalo, J.},
    TITLE = {Metacognitive aspects of elementary school students' performance on arithmetic tasks},  
    NOTE = {Paper presented at the annual meeting of the American Educational Research Association, New York},
    YEAR = {1982}
}


@BOOK{NCTM2000,
   AUTHOR = {{National Council of Teachers of Mathematics}},
   TITLE = {Principles and standards for school mathematics},
   PUBLISHER = {Author},
   ADDRESS = {Reston, VA},
   YEAR = {2000}  
}


@INCOLLECTION{Selden,
   AUTHOR = {Selden, A. and Selden, J. and Hauk, S. and Mason, A.},
   TITLE = {Why can't calculus students access their knowledge to solve nonroutine problems?},
   BOOKTITLE = {Research in Collegiate Mathematics Education. {IV}},
   EDITOR={E. Dubinsky and A. H. Schoenfeld and J. Kaput},
   PUBLISHER={American Mathematical Society},
   ADDRESS={Providence, RI},
   YEAR = {2000},
   PAGES = {128--153}
}

@INPROCEEDINGS{Tall,
   AUTHOR = {Tall, D.O.},
   TITLE = {Cognitive aspects of proof, with special reference to the irrationality of $\sqrt{2}$},      
   BOOKTITLE = {Proceedings of the  {I}nternational {C}onference for the {P}sychology of {M}athematics {E}ducation (3rd)},
   YEAR = {1979},
   PUBLISHER={University of Warwick},
   ADDRESS = {Coventry, England}, 
   PAGES = {206--207},
   EDITOR = {D. O. Tall},
   NOTE={ERIC Citation Number  ED226956}
}


@PHDTHESIS{Hauk97,
   AUTHOR = {Hauk, S.},
   TITLE = {Long-time behavior of the {S}tommel-{C}harney model of the gulf stream},
   SCHOOL = {University of California},
   ADDRESS = {Irvine, CA},
   YEAR = {1997}, 
   TYPE = {Doctoral dissertation},
   NOTE = {DAI Number AAT 9735145}
}

@UNPUBLISHED{George04,
   AUTHOR = {T. R. George},
   TITLE = {Proofs without words and wordy proofs},
   YEAR={2004}, 
   NOTE = {{\rm (Unpublished doctoral dissertation, Western State University)}}
}

@INPROCEEDINGS{Weber02,
   AUTHOR = {K. Weber,},
   TITLE = {Instrumental and relational understanding in proofs about group isomorphisms},      
   BOOKTITLE = {Proceedings of the second {I}nternational {C}onference on the {T}eaching of {M}athematics (at the undergraduate level)},
   YEAR = {2002},
   ADDRESS = {Hersonisoss, Crete, Greece},
   PUBLISHER={Wiley \& Sons},
   EDITOR={I. Vakalis and Hughes Hallett, D. and C. Kourouniotis and D. Quinney and T. Constantinos},
   NOTE={Electronic Proceedings, Paper Number 86 (pap86.pdf). Retrieved March 22, 2006 from http://www.math.uoc.gr/~ictm2/Proceedings/pap86.pdf.}
}