useful stuff

pdf:
rotate:rotate:http://www.pdfaid.com/rotate-pdf-pages-online.aspx
deletepages:deletepages:https://pdfresizer.com/delete-pages
1*2print:1*2print:https://pdfresizer.com/optimize
Sejdacrop:Sejdacrop:https://www.sejda.com/crop-pdf
%Sejdadeletepages:%Sejdadeletepages:https://www.sejda.com/delete-pdf-pages
pdfcalendar:pdfcalendar:https://www.timeanddate.com/calendar/create.html

onlinelatex:
Roger'seqn:Roger'seqn:http://rogercortesi.com/eqn/
Fulllatexcompile:Fulllatexcompile:http://latex.informatik.uni-halle.de/latex-online/latex.php
Latexmathsymbols..Latexmathsymbols..http://web.ift.uib.no/Teori/KURS/WRK/TeX/symALL.html
xymatrixforcomm.diag.:xymatrixforcomm.diag.:http://www.jmilne.org/not/Mxymatrix.pdf
tikzcdcomm.diag.:tikzcdcomm.diag.:https://tikzcd.yichuanshen.de/

Book suggestions

Book suggestions for undergrad/master students

Suppose you already learnt some abstract algebra (rings, ideals, modules etc.):

1. You should learn Galois theory. I recommend Hungerford's book ``Algebra" Chapter V (try to solve most of the exercises there).

2. More algebraic preparations: Learn some language of categories, e.g., Hungerford's book ``Algebra" Chapter X.
Learn some commutative algebra. Standard book: Atiyah-Macdonald ``Introduction to Commutative Algebra" (try to solve most of the exercises there).
Learn some homological algebra. For example, Hilton-Stambach: ``A Course in Homological Algebra", Chapter 1-4. (some of Chapter 5, 6 if you like).

3. Venturing into AG and NT. For AG, can start with Hartshorne ``Algebraic Geometry" Chapter 1-3.
For NT, Local class field theory, Serre: ``Local fields". Global CFT, Neukirch book; and/or Cassels-Frohlich book.
With some AG learnt, can learn Elliptic curves. Silverman, ``The Arithmetic of Elliptic Curves".
Relation between EC and MF, Diamond-Shurman, ``A First Course in Modular Forms".

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