The packages are loaded by tufte. You don't have to do anything:
\listfiles
\documentclass{tufte-book}
\usepackage{blindtext}% only for demo here
\let\subsubsection\subsection% dito
\begin{document}
\blinddocument
\end{document}
The filelist (can be found at the end of the logfile):
*File List*
tufte-book.cls 2009/12/11 v3.5.0 Tufte-book class
tufte-common.def 2009/12/11 v3.5.0 Common code for the Tufte-LaTeX styles
xkeyval.sty 2012/10/14 v2.6b package option processing (HA)
xkeyval.tex 2012/10/14 v2.6b key=value parser (HA)
xifthen.sty 2009/04/17 v1.3 Extended ifthen features
etex.sty 1998/03/26 v2.0 eTeX basic definition package (PEB)
calc.sty 2007/08/22 v4.3 Infix arithmetic (KKT,FJ)
ifthen.sty 2001/05/26 v1.1c Standard LaTeX ifthen package (DPC)
ifmtarg.sty 2009/09/02 v1.2a check for an empty argument
book.cls 2007/10/19 v1.4h Standard LaTeX document class
bk10.clo 2007/10/19 v1.4h Standard LaTeX file (size option)
ifpdf.sty 2011/01/30 v2.3 Provides the ifpdf switch (HO)
ifxetex.sty 2010/09/12 v0.6 Provides ifxetex conditional
titlesec.sty 2011/12/15 v2.10.0 Sectioning titles
titletoc.sty 2011/12/15 v1.6 TOC entries
hyperref.sty 2012/11/06 v6.83m Hypertext links for LaTeX
hobsub-hyperref.sty 2012/05/28 v1.13 Bundle oberdiek, subset hyperref (HO)
hobsub-generic.sty 2012/05/28 v1.13 Bundle oberdiek, subset generic (HO)
hobsub.sty 2012/05/28 v1.13 Construct package bundles (HO)
infwarerr.sty 2010/04/08 v1.3 Providing info/warning/error messages (HO)
ltxcmds.sty 2011/11/09 v1.22 LaTeX kernel commands for general use (HO)
ifluatex.sty 2010/03/01 v1.3 Provides the ifluatex switch (HO)
ifvtex.sty 2010/03/01 v1.5 Detect VTeX and its facilities (HO)
intcalc.sty 2007/09/27 v1.1 Expandable calculations with integers (HO)
[...]