\documentclass[tikz,border=5pt]{standalone}

\usepackage{amsmath}
\usepackage{circuitikz}
\usetikzlibrary{
    calc,
    arrows.meta,
    decorations.pathmorphing
}

\begin{document}

\begin{circuitikz}[
    line width=1.35pt,
    line cap=round,
    line join=round,
    >=Latex,
    font=\Large
]

% ============================================================
% Resistor style
% ============================================================

\tikzset{
    resistor/.style={
        decorate,
        decoration={
            zigzag,
            segment length=8.0pt,
            amplitude=5.2pt
        }
    }
}

% ============================================================
% Main geometry
% ============================================================

\coordinate (C)  at ( 0.00, 0.00);

\coordinate (L)  at (-4.40, 0.00);
\coordinate (TL) at (-2.10, 3.80);
\coordinate (TR) at ( 2.22, 3.80);
\coordinate (R)  at ( 4.40, 0.00);
\coordinate (BR) at ( 2.26,-3.72);
\coordinate (BL) at (-2.28,-3.72);

% ============================================================
% Outer upper-left branch
% ============================================================

\coordinate (UL1) at ($(L)!0.25!(TL)$);
\coordinate (UL2) at ($(L)!0.67!(TL)$);

\draw (L) -- (UL1);
\draw[resistor] (UL1) -- (UL2);
\draw (UL2) -- (TL);

\node at (-3.79,1.88) {$R$};

% ============================================================
% Top branch: Ig1 + R
% ============================================================

\coordinate (Ig1) at (-0.91,3.80);

\draw
    (TL)
    --
    ($(Ig1)+(-0.62,0)$);

\draw
    (Ig1)
    circle[radius=0.62];

\draw[-{Latex[length=8pt,width=8pt]},line width=1.5pt]
    ($(Ig1)+(0.30,0)$)
    --
    ($(Ig1)+(-0.31,0)$);

\draw
    ($(Ig1)+(0.62,0)$)
    --
    (0.04,3.80);

\draw[resistor]
    (0.04,3.80)
    --
    (1.14,3.80);

\draw
    (1.14,3.80)
    --
    (TR);

\node at (-0.91,4.77) {$I_{g1}$};
\node at (0.59,4.36) {$R$};

% ============================================================
% Outer upper-right branch
% ============================================================

\coordinate (UR1) at ($(TR)!0.25!(R)$);
\coordinate (UR2) at ($(TR)!0.67!(R)$);

\draw (TR) -- (UR1);
\draw[resistor] (UR1) -- (UR2);
\draw (UR2) -- (R);

\node at (3.75,1.88) {$R$};

% ============================================================
% Outer lower-right branch
% ============================================================

\coordinate (LR1) at ($(R)!0.26!(BR)$);
\coordinate (LR2) at ($(R)!0.67!(BR)$);

\draw (R) -- (LR1);
\draw[resistor] (LR1) -- (LR2);
\draw (LR2) -- (BR);

\node at (3.72,-1.88) {$R$};

% ============================================================
% Bottom branch: E3 + R
% ============================================================

\coordinate (E3) at (-1.01,-3.72);

\draw
    (BL)
    --
    ($(E3)+(-0.62,0)$);

\draw
    (E3)
    circle[radius=0.62];

\draw
    ($(E3)+(0.62,0)$)
    --
    (0.02,-3.72);

\draw[resistor]
    (0.02,-3.72)
    --
    (1.15,-3.72);

\draw
    (1.15,-3.72)
    --
    (BR);

\node at (-1.23,-4.48) {$+$};
\node at (-1.00,-5.08) {$E_3$};
\node at (0.59,-4.36) {$R$};

% ============================================================
% Outer lower-left branch: E2 + R
% ============================================================

\coordinate (E2) at (-3.70,-1.08);

\draw
    (L)
    --
    ($(E2)!0.62cm!(L)$);

\draw
    (E2)
    circle[radius=0.62];

\coordinate (E2out)
    at ($(E2)!0.62cm!(BL)$);

\coordinate (LL1)
    at ($(E2out)!0.28!(BL)$);

\coordinate (LL2)
    at ($(E2out)!0.70!(BL)$);

\draw
    (E2out)
    --
    (LL1);

\draw[resistor]
    (LL1)
    --
    (LL2);

\draw
    (LL2)
    --
    (BL);

\node at (-4.76,-0.80) {$+$};
\node at (-4.80,-1.84) {$E_2$};
\node at (-3.67,-2.91) {$R$};

% ============================================================
% Horizontal branch: Ig2
% ============================================================

\coordinate (Ig2) at (-2.05,0);

\draw
    (L)
    --
    ($(Ig2)+(-0.62,0)$);

\draw
    (Ig2)
    circle[radius=0.62];

\draw[-{Latex[length=8pt,width=8pt]},line width=1.5pt]
    ($(Ig2)+(-0.30,0)$)
    --
    ($(Ig2)+(0.31,0)$);

\draw
    ($(Ig2)+(0.62,0)$)
    --
    (C);

\node at (-2.06,1.10) {$I_{g2}$};

% ============================================================
% Horizontal branch: Ig3
% ============================================================

\coordinate (Ig3) at (2.07,0);

\draw
    (C)
    --
    ($(Ig3)+(-0.62,0)$);

\draw
    (Ig3)
    circle[radius=0.62];

\draw[-{Latex[length=8pt,width=8pt]},line width=1.5pt]
    ($(Ig3)+(-0.30,0)$)
    --
    ($(Ig3)+(0.31,0)$);

\draw
    ($(Ig3)+(0.62,0)$)
    --
    (R);

\node at (2.08,1.10) {$I_{g3}$};

% ============================================================
% Internal upper-left resistor
% ============================================================

\coordinate (IUL1)
    at ($(TL)!0.27!(C)$);

\coordinate (IUL2)
    at ($(TL)!0.66!(C)$);

\draw
    (TL)
    --
    (IUL1);

\draw[resistor]
    (IUL1)
    --
    (IUL2);

\draw
    (IUL2)
    --
    (C);

\node at (-1.36,1.88) {$R$};

% ============================================================
% Internal lower-left resistor
% ============================================================

\coordinate (ILL1)
    at ($(C)!0.31!(BL)$);

\coordinate (ILL2)
    at ($(C)!0.68!(BL)$);

\draw
    (C)
    --
    (ILL1);

\draw[resistor]
    (ILL1)
    --
    (ILL2);

\draw
    (ILL2)
    --
    (BL);

\node at (-1.33,-1.88) {$R$};

% ============================================================
% Internal upper-right source E1
% ============================================================

\coordinate (E1) at (1.20,2.10);

\draw
    (C)
    --
    ($(E1)!0.62cm!(C)$);

\draw
    (E1)
    circle[radius=0.62];

\draw
    ($(E1)!0.62cm!(TR)$)
    --
    (TR);

\node at (0.83,2.97) {$E_1$};
\node[rotate=-31] at (0.87,3.31) {$+$};

% ============================================================
% Internal lower-right source E4
% ============================================================

\coordinate (E4) at (1.24,-2.07);

\draw
    (C)
    --
    ($(E4)!0.62cm!(C)$);

\draw
    (E4)
    circle[radius=0.62];

\draw
    ($(E4)!0.62cm!(BR)$)
    --
    (BR);

\node at (2.06,-1.67) {$E_4$};
\node[rotate=-31] at (2.20,-2.14) {$+$};

% ============================================================
% Junction dots
% ============================================================

\fill (L)  circle[radius=4.2pt];
\fill (TL) circle[radius=4.2pt];
\fill (TR) circle[radius=4.2pt];
\fill (R)  circle[radius=4.2pt];
\fill (BR) circle[radius=4.2pt];
\fill (BL) circle[radius=4.2pt];
\fill (C)  circle[radius=4.2pt];

\end{circuitikz}

\end{document}