List of LaTeX symbol to import in aText. Write the LaTeX command prepended by a ; and the text substition inserts the Unicode symbol for this LaTeX character. Based on this list: http://www.cl.cam.ac.uk/~mgk25/ucs/examples/TeX.txt, but expanded (and expandable) -- see comments!

LaTeX Symbols.csv

;\aleph,ℵ
;\forall,∀
;\hbar,ℏ
;\emptyset,∅
;\exists,∃
;\imath,ı
;\nabla,∇
;\neg,¬
;\surd,√
;\flat,♭
;\ell,ℓ
;\top,⊤
;\natural,♮
;\wp,℘
;\bot,⊥
;\sharp,♯
;\Re,ℜ
;\|,∥
;\clubsuit,♣
;\Im,ℑ
;\angle,∠
;\diamondsuit,♢
;\partial,∂
;\triangle,△
;\heartsuit,♡
;\infty,∞
;\backslash,\
;\spadesuit,♠
;\Box,□
;\Diamond,◇
;\sum,∑
;\bigcap,⋂
;\bigodot,⨀
;\prod,∏
;\bigcup,⋃
;\bigotimes,⨂
;\coprod,∐
;\bigsqcup,⨆
;\bigoplus,⨁
;\int,∫
;\bigvee,⋁
;\biguplus,⨄
;\oint,∮
;\bigwedge,⋀
;\pm,±
;\cap,∩
;\vee,∨
;\mp,∓
;\cup,∪
;\wedge,∧
;\setminus,∖
;\uplus,⊎
;\oplus,⊕
;\cdot,⋅
;\sqcap,⊓
;\ominus,⊖
;\times,×
;\sqcup,⊔
;\otimes,⊗
;\ast,∗
;\triangleleft,◁
;\oslash,⊘
;\star,⋆
;\triangleright,▷
;\odot,⊙
;\diamond,⋄
;\wr,≀
;\dagger,†
;\circ,∘
;\bigcirc,◯
;\ddagger,‡
;\bullet,∙
;\bigtriangleup,△
;\amalg,⨿
;\div,÷
;\bigtriangledown,▽
;\unlhd,⊴
;\lhd,⊲
;\rhd,⊳
;\unrhd,⊵
;\leq,≤
;\geq,≥
;\equiv,≡
;\prec,≺
;\succ,≻
;\sim,∼
;\preceq,≼
;\succeq,≽
;\simeq,≃
;\ll,≪
;\gg,≫
;\asymp,≍
;\subset,⊂
;\supset,⊃
;\approx,≈
;\subseteq,⊆
;\supseteq,⊇
;\cong,≅
;\sqsubseteq,⊑
;\sqsupseteq,⊒
;\bowtie,⋈
;\in,∈
;\ni,∋
;\propto,∝
;\vdash,⊢
;\dashv,⊣
;\models,⊨
;\smile,⌣
;\mid,∣
;\doteq,≐
;\frown,⌢
;\parallel,∥
;\perp,⊥
;\sqsubset,⊏
;\sqsupset,⊐
;\Join,⨝
;\not<,≮
;\not>,≯
;\not=,≠
;\not\leq,≰
;\not\geq,≱
;\not\equiv,≢
;\not\prec,⊀
;\not\succ,⊁
;\not\sim,≁
;\not\preceq,⋠
;\not\succeq,⋡
;\not\simeq,≄
;\not\subset,⊄
;\not\supset,⊅
;\not\approx,≉
;\not\subseteq,⊈
;\not\supseteq,⊉
;\not\cong,≇
;\not\sqsubseteq,⋢
;\not\sqsupseteq,⋣
;\not\asymp,≭
;\leftarrow,←
;\longleftarrow,⟵
;\uparrow,↑
;\Leftarrow,⇐
;\Longleftarrow,⟸
;\Uparrow,⇑
;\rightarrow,→
;\longrightarrow,⟶
;\downarrow,↓
;\Rightarrow,⇒
;\Longrightarrow,⟹
;\Downarrow,⇓
;\leftrightarrow,↔
;\longleftrightarrow,⟷
;\updownarrow,↕
;\Leftrightarrow,⇔
;\Longleftrightarrow,⟺
;\Updownarrow,⇕
;\mapsto,↦
;\longmapsto,⟼
;\nearrow,↗
;\hookleftarrow,↩
;\hookrightarrow,↪
;\searrow,↘
;\leftharpoonup,↼
;\rightharpoonup,⇀
;\swarrow,↙
;\leftharpoondown,↽
;\rightharpoondown,⇁
;\nwarrow,↖
;\rightleftharpoons,⇌
;\leadsto,↝
;\lbrack,[
;\lfloor,⌊
;\lceil,⌈
;[\![,⟦
;\lbrace,{
;\langle,⟨
;\langle\!\langle,⟪
;\rbrack,]
;\rfloor,⌋
;\rceil,⌉
;]\!],⟧
;\rbrace,}
;\rangle,⟩
;\rangle\!\rangle,⟫
≠\neq
;\leq,≤
;\geq,≥
;\lbrace,{
;\rbrace,}
;\to,→
;\gets,←
;\owns,∋
;\land,∧
;\lor,∨
;\lnot,¬
;\vert,∣
;\Vert,∥
;\vdots,⋮
;\cdots,⋯
;\ddots,⋱
;\thinspace, 
;\oe,œ
;\OE,Œ
;\ae,æ
;\AE,Æ
;\aa,å
;\AA,Å
;\o,ø
;\O,Ø
;\l,ł
;\L,Ł
;\ss,ß
;\S,§
;\P,¶
;\dag,†
;\ddag,‡
;\copyright,©
;\pounds,£
;\ldots,…
;\circeq,≗
;\circlearrowleft,⥀
;\circlearrowright,⥁
;\circledS,Ⓢ
;\circledast,⊛
;\circledcirc,⊚
;\circleddash,⊝

This Wikipedia page lists probably all LaTeX symbols: http://ia.wikipedia.org/wiki/Wikipedia:LaTeX_symbols
Here is a Unicode name → LaTeX symbol map: https://gist.github.com/piquadrat/798549
This website gives you Unicode name → Unicode symbol: http://www.fileformat.info/info/unicode/char/search.htm

Here's also a list, with a few more stuff. http://milde.users.sourceforge.net/LUCR/Math/unimathsymbols.xhtml

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